In Press
In Press articles are edited and published online ahead of issue. When the final article is assigned to volumes/issues, the Article in Press version will be removed and the final version will appear in the associated published volumes/issues.
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High-responsivity and high-speed germanium photodetector for C + L application
Yiling Hu, Zhipeng Liu, Zhi Liu, Yupeng Zhu, Tao men, Guangze Zhang, Jun Zheng, Yuhua Zuo, Buwen Cheng
, Available online  
doi: 10.1088/1674-4926/25030017

A silicon-based germanium (Ge) photodetector working for C and L bands is proposed in this paper. The device features a novel asymmetric PIN structure, which contributes to a more optimized electric field distribution in Ge and a shorter effective width of depleted region. Meanwhile, the optical structure is designed carefully to enhance responsivity for broadband. Under −7 V, where the weak avalanche process happens, the responsivity of our device is 1.49 and 1.16 A/W at 1550 and 1600 nm, with bandwidth of 47.1 and 44.5 GHz, respectively. These performances demonstrate the significant application potential of the device in optical communication systems.

A silicon-based germanium (Ge) photodetector working for C and L bands is proposed in this paper. The device features a novel asymmetric PIN structure, which contributes to a more optimized electric field distribution in Ge and a shorter effective width of depleted region. Meanwhile, the optical structure is designed carefully to enhance responsivity for broadband. Under −7 V, where the weak avalanche process happens, the responsivity of our device is 1.49 and 1.16 A/W at 1550 and 1600 nm, with bandwidth of 47.1 and 44.5 GHz, respectively. These performances demonstrate the significant application potential of the device in optical communication systems.
GaN diodes comparative study for high energy protons detection
Matilde Siviero, Maxime Hugues, Lucas Lesourd, Eric Frayssinet, Shirley Prado de la Cruz, Sebastien Chenot, Johan-Petter Hofverberg, Marie Vidal, Jean-Yves Duboz
, Available online  
doi: 10.1088/1674-4926/25020014

GaN diodes for high energy (64.8 MeV) proton detection were fabricated and investigated. A comparison of the performance of GaN diodes with different structures is presented, with a focus on sapphire and on GaN substrates, Schottky and pin diodes, and different active layer thicknesses. Pin diodes fabricated on a sapphire substrate are the best choice for a GaN proton detector working at 0 V bias. They are sensitive (minimum detectable proton beam <1 pA/cm2), linear as a function of proton current and fast (<1 s). High proton current sensitivity and high spatial resolution of GaN diodes can be exploited in the future for proton imaging of patients in proton therapy.

GaN diodes for high energy (64.8 MeV) proton detection were fabricated and investigated. A comparison of the performance of GaN diodes with different structures is presented, with a focus on sapphire and on GaN substrates, Schottky and pin diodes, and different active layer thicknesses. Pin diodes fabricated on a sapphire substrate are the best choice for a GaN proton detector working at 0 V bias. They are sensitive (minimum detectable proton beam <1 pA/cm2), linear as a function of proton current and fast (<1 s). High proton current sensitivity and high spatial resolution of GaN diodes can be exploited in the future for proton imaging of patients in proton therapy.
4H-SiC superjunction MOSFET with integrated high-K gate dielectric and split gate
Jiafei Yao, Zhengfei Yang, Yuxuan Dai, Ziwei Hu, Man Li, Kemeng Yang, Jing Chen, Maolin Zhang, Jun Zhang, Yufeng Guo
, Available online  
doi: 10.1088/1674-4926/25010005

A 4H-SiC superjunction (SJ) MOSFET (SJMOS) with integrated high-K gate dielectric and split gate (HKSG-SJMOS) is proposed in this paper. The key features of HKSG-SJMOS involve the utilization of high-K (HK) dielectric as the gate dielectric, which surrounds the source-connected split gate (SG) and metal gate. The high-K gate dielectric optimizes the electric field distribution within the drift region, creating a low-resistance conductive channel. This enhancement leads to an increase in the breakdown voltage (BV) and a reduction in the specific on resistance (Ron,sp). The introduction of split gate surrounded by high-K dielectric reduces the gate−drain capacitance (Cgd) and gate−drain charge (Qgd), which improves the switching characteristics. The simulation results indicate that compared to conventional 4H-SiC SJMOS, the HKSG-SJMOS exhibits a 110.5% enhancement in figure of merit (FOM, FOM = BV2/Ron,sp), a 93.6% reduction in the high frequency figure of merit (HFFOM) of Ron,sp·Cgd, and reductions in turn-on loss (Eon) and turn-off loss (Eoff) by 38.3% and 31.6%, respectively. Furthermore, the reverse recovery characteristics of HKSG-SJMOS has also discussed, revealing superior performance compared to conventional 4H-SiC SJMOS.

A 4H-SiC superjunction (SJ) MOSFET (SJMOS) with integrated high-K gate dielectric and split gate (HKSG-SJMOS) is proposed in this paper. The key features of HKSG-SJMOS involve the utilization of high-K (HK) dielectric as the gate dielectric, which surrounds the source-connected split gate (SG) and metal gate. The high-K gate dielectric optimizes the electric field distribution within the drift region, creating a low-resistance conductive channel. This enhancement leads to an increase in the breakdown voltage (BV) and a reduction in the specific on resistance (Ron,sp). The introduction of split gate surrounded by high-K dielectric reduces the gate−drain capacitance (Cgd) and gate−drain charge (Qgd), which improves the switching characteristics. The simulation results indicate that compared to conventional 4H-SiC SJMOS, the HKSG-SJMOS exhibits a 110.5% enhancement in figure of merit (FOM, FOM = BV2/Ron,sp), a 93.6% reduction in the high frequency figure of merit (HFFOM) of Ron,sp·Cgd, and reductions in turn-on loss (Eon) and turn-off loss (Eoff) by 38.3% and 31.6%, respectively. Furthermore, the reverse recovery characteristics of HKSG-SJMOS has also discussed, revealing superior performance compared to conventional 4H-SiC SJMOS.
Green perovskite CsPbBr3 light-emitting electrochemical cells with distributed Si nanowires-based electrodes for flexible applications
Viktoriia Mastalieva, Anastasiya Yakubova, Maria Baeva, Vladimir Neplokh, Dmitry M. Mitin, Vladimir Fedorov, Alexander Goltaev, Alexey Mozharov, Fedor Kochetkov, Andrei S. Toikka, Ramazan Kenesbay, Ekaterina Vyacheslavova, Alexander Vorobyev, Kristina Novikova, Dmitry Krasnikov, Jianjun Tian, Albert G. Nasibulin, Alexander Gudovskikh, Sergey Makarov, Ivan Mukhin
, Available online  
doi: 10.1088/1674-4926/24120010

The emergence of cesium lead halide perovskite materials stable at air opened new prospects for the optoelectronic industry. In this work we present an approach to fabricating a flexible green perovskite light-emitting electrochemical cell (PeLEC) with a CsPbBr3 perovskite active layer using a highly-ordered silicon nanowire (Si NW) array as a distributed electrode integrated within a thin polydimethylsiloxane film (PDMS). Numerical simulations reveal that Si NWs-based distributed electrode aids the improvement of carrier injection into the perovskite layer with an increased thickness and, therefore, the enhancement of light-emitting performance. The X-ray diffraction study shows that the perovskite layer synthesized on the PDMS membrane with Si NWs has a similar crystal structure to the ones synthesized on planar Si wafers. We perform a comparative analysis of the light-emitting devices’ properties fabricated on rigid silicon substrates and flexible Si NW-based membranes released from substrates. Due to possible potential barriers in a flexible PeLEC between the bottom electrode (made of a network of single-walled carbon nanotube film) and Si NWs, the electroluminescence performance and I ̶ V properties of flexible devices deteriorated compared to rigid devices. The developed PeLECs pave the way for further development of inorganic flexible uniformly light-emitting devices with improved properties.

The emergence of cesium lead halide perovskite materials stable at air opened new prospects for the optoelectronic industry. In this work we present an approach to fabricating a flexible green perovskite light-emitting electrochemical cell (PeLEC) with a CsPbBr3 perovskite active layer using a highly-ordered silicon nanowire (Si NW) array as a distributed electrode integrated within a thin polydimethylsiloxane film (PDMS). Numerical simulations reveal that Si NWs-based distributed electrode aids the improvement of carrier injection into the perovskite layer with an increased thickness and, therefore, the enhancement of light-emitting performance. The X-ray diffraction study shows that the perovskite layer synthesized on the PDMS membrane with Si NWs has a similar crystal structure to the ones synthesized on planar Si wafers. We perform a comparative analysis of the light-emitting devices’ properties fabricated on rigid silicon substrates and flexible Si NW-based membranes released from substrates. Due to possible potential barriers in a flexible PeLEC between the bottom electrode (made of a network of single-walled carbon nanotube film) and Si NWs, the electroluminescence performance and I ̶ V properties of flexible devices deteriorated compared to rigid devices. The developed PeLECs pave the way for further development of inorganic flexible uniformly light-emitting devices with improved properties.
Magnetron sputter and phase change optimization of wafer-level GeTe films for RF switch
Shihang Liu, Hanxiang Jia, Shuangzan Lu, Changyu Hu, Jun Liu
, Available online  
doi: 10.1088/1674-4926/24120033

With the rapid advancement of 5G communication technology, increasingly stringent demands are placed on the performance and functionality of phase change switches. Given that RF and microwave signals exhibit characteristics of high frequency, high speed, and high precision, it is imperative for phase change switches to possess fast, accurate, and reliable switching capabilities. Moreover, wafer-level compositional homogeneity and resistivity uniformity during semiconductor manufacturing are crucial for ensuring the yield and reliability of RF switches. By controlling magnetron sputter of GeTe through from four key parameters (pressure, power, Ar flow, and post-annealing) and incorporating elemental proportional compensation in the target, we achieved effective modulation over GeTe uniformity. Finally, we successfully demonstrated the process integration of GeTe phase-change RF switches on 6-inch scaled wafers.

With the rapid advancement of 5G communication technology, increasingly stringent demands are placed on the performance and functionality of phase change switches. Given that RF and microwave signals exhibit characteristics of high frequency, high speed, and high precision, it is imperative for phase change switches to possess fast, accurate, and reliable switching capabilities. Moreover, wafer-level compositional homogeneity and resistivity uniformity during semiconductor manufacturing are crucial for ensuring the yield and reliability of RF switches. By controlling magnetron sputter of GeTe through from four key parameters (pressure, power, Ar flow, and post-annealing) and incorporating elemental proportional compensation in the target, we achieved effective modulation over GeTe uniformity. Finally, we successfully demonstrated the process integration of GeTe phase-change RF switches on 6-inch scaled wafers.
A 1.25 μW/ch TDM-based analog front-end using a charge-sharing multiplexer for bio-potential recording
Yifan Huang, Jing Wang, Lin Cheng
, Available online  
doi: 10.1088/1674-4926/24120034

This paper presents the design of a low-power multi-channel analog front-end (AFE) for bio-potential recording. By using time division multiplexing (TDM), a successive approximation register analog-to-digital converter (SAR ADC) is shared among all 20 channels. A charge-sharing multiplexer (MUX) is proposed to transmit the output signals from the respective channels to the ADC. By separately pre sampling the output of each channel, the sampling time of each channel is greatly extended and additional active buffers are avoided. The AFE is fabricated in a 65-nm CMOS process, and the whole system consumes 28.2 μW under 1 V supply. Each analog acquisition channel consumes 1.25 μW and occupies a chip area of 0.14 mm2. Measurement results show that the AFE achieves an input referred noise of 1.8 μV∙rms in a 350 Hz bandwidth and a noise efficiency factor (NEF) of 4.1. The 12-bit SAR ADC achieves an ENOB of 9.8 bit operating at 25 kS/s. The AFE is experimented on real-world applications by measuring human ECG and a clear ECG waveform is captured.

This paper presents the design of a low-power multi-channel analog front-end (AFE) for bio-potential recording. By using time division multiplexing (TDM), a successive approximation register analog-to-digital converter (SAR ADC) is shared among all 20 channels. A charge-sharing multiplexer (MUX) is proposed to transmit the output signals from the respective channels to the ADC. By separately pre sampling the output of each channel, the sampling time of each channel is greatly extended and additional active buffers are avoided. The AFE is fabricated in a 65-nm CMOS process, and the whole system consumes 28.2 μW under 1 V supply. Each analog acquisition channel consumes 1.25 μW and occupies a chip area of 0.14 mm2. Measurement results show that the AFE achieves an input referred noise of 1.8 μV∙rms in a 350 Hz bandwidth and a noise efficiency factor (NEF) of 4.1. The 12-bit SAR ADC achieves an ENOB of 9.8 bit operating at 25 kS/s. The AFE is experimented on real-world applications by measuring human ECG and a clear ECG waveform is captured.
A 32Gb/s digital-assisted PAM-4 DFB laser driver in 28-nm CMOS
Yang Min, Nan Qi, Yihan Chen, Yinye Zhu, Guike Li, Yonghui Lin, Zhao Zhang, Jian Liu, Nanjian Wu, Jingbo Shi, Frank F. Shi, Liyuan Liu
, Available online  
doi: 10.1088/1674-4926/25020011

This paper presents a 4-level pulse amplitude modulation (PAM-4) distributed feedback (DFB) laser driver. The driver adopts a digital slicing architecture to achieve high linearity by adjusting the weights of three thermometer-coded main paths. An efficient-biased output stage structure is proposed to reduce power consumption while avoiding the degradation of output node bandwidth typically induced by parasitic capacitance in high-current bias path. A two-tap linear and nonlinear feed-forward equalizer (FFE) is implemented in the digital domain to extend bandwidth limitations and compensate for the dynamic nonlinearity of the DFB laser. The nonlinear FFE is realized at the cost of lower power consumption and smaller area by utilizing the simultaneity of low-speed parallel data. The chip is fabricated in 28 nm CMOS process. Measurement results indicate that, with a laser bias current of 40 mA, a modulation current of 20 mApp, and an operating rate of 32 Gb/s PAM-4, the overall power consumption of the chip is 372 mW, corresponding to an energy efficiency of 11.6 pJ/b.

This paper presents a 4-level pulse amplitude modulation (PAM-4) distributed feedback (DFB) laser driver. The driver adopts a digital slicing architecture to achieve high linearity by adjusting the weights of three thermometer-coded main paths. An efficient-biased output stage structure is proposed to reduce power consumption while avoiding the degradation of output node bandwidth typically induced by parasitic capacitance in high-current bias path. A two-tap linear and nonlinear feed-forward equalizer (FFE) is implemented in the digital domain to extend bandwidth limitations and compensate for the dynamic nonlinearity of the DFB laser. The nonlinear FFE is realized at the cost of lower power consumption and smaller area by utilizing the simultaneity of low-speed parallel data. The chip is fabricated in 28 nm CMOS process. Measurement results indicate that, with a laser bias current of 40 mA, a modulation current of 20 mApp, and an operating rate of 32 Gb/s PAM-4, the overall power consumption of the chip is 372 mW, corresponding to an energy efficiency of 11.6 pJ/b.
A Cryogenic 3.3-V supply, 1.6% 3σ-accuracy all-CMOS voltage reference with 58-dB PSR@10 kHz in 0.18-μm CMOS
Yupeng Yuan, Yi Zhuo, Jianjun Tu, Qingjiang Xia, Yan Zhang, Wengao Lu, Xiangyang Li, Ding Ma
, Available online  
doi: 10.1088/1674-4926/24120039

This brief presents a cryogenic voltage reference circuit designed to operate effectively across a wide temperature range from 30 to 300 K. A key feature of the proposed design is utilizing a current subtraction technique for temperature compensation of the reference current, avoiding the deployment of bipolar transistors to reduce area and power consumption. Implemented with a 0.18-µm CMOS process, the circuit achieves a temperature coefficient (TC) of 67.5 ppm/K, which was not achieved in previous works. The design can also attain a power supply rejection (PSR) of 58 dB at 10 kHz. Meanwhile, the average reference voltage is 1.2 V within a 1.6% 3σ-accuracy spread. Additionally, the design is characterized by a minimal power dissipation of 1 µW at 30 K and a compact chip area of 0.0035 mm².

This brief presents a cryogenic voltage reference circuit designed to operate effectively across a wide temperature range from 30 to 300 K. A key feature of the proposed design is utilizing a current subtraction technique for temperature compensation of the reference current, avoiding the deployment of bipolar transistors to reduce area and power consumption. Implemented with a 0.18-µm CMOS process, the circuit achieves a temperature coefficient (TC) of 67.5 ppm/K, which was not achieved in previous works. The design can also attain a power supply rejection (PSR) of 58 dB at 10 kHz. Meanwhile, the average reference voltage is 1.2 V within a 1.6% 3σ-accuracy spread. Additionally, the design is characterized by a minimal power dissipation of 1 µW at 30 K and a compact chip area of 0.0035 mm².
Research on heterojunction semiconductor photodetectors based on CsPbBr3 QDs/CsPbBrxI3–x QDs
Chenguang Shen, Mengwei Chen, Wei Huang, Yingping Yang
, Available online  
doi: 10.1088/1674-4926/25010022

All-inorganic CsPbBr3 perovskite quantum dots (QDs) have attracted extensive attention in photoelectric detection for their excellent photoelectric properties and stability. However, the CsPbBr3 quantum dot film exhibits a high non-radiative recombination rate, and the mismatch in energy levels with the carbon electrode weakens hole extraction efficiency. These reduces the device's performance. To improve this, a semiconductor photodetector based on fluorine-doped tin oxide (FTO)/dense titanium dioxide (c-TiO2)/mesoporous titanium dioxide (m-TiO2)/CsPbBr3 QDs/CsPbBrxI3–x (x = 2, 1.5, 1) QDs/C structure was studied. By adjusting the Br : I ratio, the synthesized CsPbBrxI3–x (x = 2, 1.5, 1) QDs showed an adjustable band gap width of 2.284−2.394 eV. And forming a type Ⅱ band structure with CsPbBr3 QDs, which reduced the valence band offset between the active layer and the carbon electrode, this promoted carrier extraction and reduced non-radiative recombination rate. Compared with the original device (the photosensitive layer is CsPbBr3 QDs), the performance of the photodetector based on the CsPbBr3 QDs/CsPbBr2I QDs heterostructure is significantly improved, the responsivity (R) increased by 73%, the specific detectivity rate (D*) increased from 6.98 × 1012 to 3.19 × 1013 Jones, the on/off ratio reached 106. This study provides a new idea for the development of semiconductor tandem detectors.

All-inorganic CsPbBr3 perovskite quantum dots (QDs) have attracted extensive attention in photoelectric detection for their excellent photoelectric properties and stability. However, the CsPbBr3 quantum dot film exhibits a high non-radiative recombination rate, and the mismatch in energy levels with the carbon electrode weakens hole extraction efficiency. These reduces the device's performance. To improve this, a semiconductor photodetector based on fluorine-doped tin oxide (FTO)/dense titanium dioxide (c-TiO2)/mesoporous titanium dioxide (m-TiO2)/CsPbBr3 QDs/CsPbBrxI3–x (x = 2, 1.5, 1) QDs/C structure was studied. By adjusting the Br : I ratio, the synthesized CsPbBrxI3–x (x = 2, 1.5, 1) QDs showed an adjustable band gap width of 2.284−2.394 eV. And forming a type Ⅱ band structure with CsPbBr3 QDs, which reduced the valence band offset between the active layer and the carbon electrode, this promoted carrier extraction and reduced non-radiative recombination rate. Compared with the original device (the photosensitive layer is CsPbBr3 QDs), the performance of the photodetector based on the CsPbBr3 QDs/CsPbBr2I QDs heterostructure is significantly improved, the responsivity (R) increased by 73%, the specific detectivity rate (D*) increased from 6.98 × 1012 to 3.19 × 1013 Jones, the on/off ratio reached 106. This study provides a new idea for the development of semiconductor tandem detectors.
A miniaturized wireless electrical impedance myography platform for the long-term adaptive muscle fatigue monitoring
Shanshan Yu, Yichao Gan, Feifan Song, Qiongzhang Wang, Hao Tang, Zhao Li
, Available online  
doi: 10.1088/1674-4926/25020029

Accurate quantification of exercise interventions and changes in muscle function is essential for personalized health management. Electrical impedance myography (EIM) technology offers an innovative, noninvasive, painless, and easy-to-perform solution for muscle health monitoring. However, current EIM platforms face a number of limitations, including large device size, wired connections, and instability of the electrode-skin interface, which limit their applicability for monitoring muscle movement. In this study, a miniature wireless EIM platform with a user-friendly smartphone app is proposed and developed. The miniature, wireless, multi-frequency (20 kHz−1 MHz) EIM platform is equipped with flexible microneedle array electrodes (MAE). The advantages of MAEs over conventional electrodes were demonstrated by physical field modeling simulations and skin-electrode contact impedance comparison tests. The smartphone APP was developed to wirelessly operate the EIM platform, and to transmit and process real-time muscle impedance data. To validate its effectiveness, a seven-day adaptive fatigue training study was conducted, which demonstrated that the EIM platform was able to detect muscle adaptations and serve as a reliable indicator of fatigue. This study presents an innovative approach to applying EIM technology to muscle health monitoring and exercise testing, thereby advancing the development of personalized health management and athletic performance assessment.

Accurate quantification of exercise interventions and changes in muscle function is essential for personalized health management. Electrical impedance myography (EIM) technology offers an innovative, noninvasive, painless, and easy-to-perform solution for muscle health monitoring. However, current EIM platforms face a number of limitations, including large device size, wired connections, and instability of the electrode-skin interface, which limit their applicability for monitoring muscle movement. In this study, a miniature wireless EIM platform with a user-friendly smartphone app is proposed and developed. The miniature, wireless, multi-frequency (20 kHz−1 MHz) EIM platform is equipped with flexible microneedle array electrodes (MAE). The advantages of MAEs over conventional electrodes were demonstrated by physical field modeling simulations and skin-electrode contact impedance comparison tests. The smartphone APP was developed to wirelessly operate the EIM platform, and to transmit and process real-time muscle impedance data. To validate its effectiveness, a seven-day adaptive fatigue training study was conducted, which demonstrated that the EIM platform was able to detect muscle adaptations and serve as a reliable indicator of fatigue. This study presents an innovative approach to applying EIM technology to muscle health monitoring and exercise testing, thereby advancing the development of personalized health management and athletic performance assessment.
Dynamic avalanche reliability enhancement of FS-IGBT under unclamped inductive switching
Jingping Zhang, Houcai Luo, Huan Wu, Bofeng Zheng, Xianping Chen
, Available online  
doi: 10.1088/1674-4926/25020006

The dynamic avalanche effect is a critical factor influencing the performance and reliability of the field-stop insulated gate bipolar transistors (FS-IGBT). Unclamped inductive switching (UIS) is the primary method for testing the dynamic avalanche capability of FS-IGBTs. Numerous studies have demonstrated that factors such as device structure, avalanche-generating current filaments, and electrical parameters influence the dynamic avalanche effect of the FS-IGBT. However, few studies have focused on enhancing the avalanche reliability of the FS-IGBT by adjusting circuit parameters during operation. In this paper, the dynamic avalanche effect of the FS-IGBT under UIS conditions is comprehensively investigated through a series of comparative experiments with varying circuit parameters, including bus voltage VDC, gate voltage VG, gate resistance Rg, load inductance L, and temperature TC. Furthermore, a method to enhance the dynamic avalanche reliability of the FS-IGBT under UIS by optimizing circuit parameters is proposed. In practical applications, reducing gate voltage, increasing load inductance, and lowering temperature can effectively improve the dynamic avalanche capability of the FS-IGBT.

The dynamic avalanche effect is a critical factor influencing the performance and reliability of the field-stop insulated gate bipolar transistors (FS-IGBT). Unclamped inductive switching (UIS) is the primary method for testing the dynamic avalanche capability of FS-IGBTs. Numerous studies have demonstrated that factors such as device structure, avalanche-generating current filaments, and electrical parameters influence the dynamic avalanche effect of the FS-IGBT. However, few studies have focused on enhancing the avalanche reliability of the FS-IGBT by adjusting circuit parameters during operation. In this paper, the dynamic avalanche effect of the FS-IGBT under UIS conditions is comprehensively investigated through a series of comparative experiments with varying circuit parameters, including bus voltage VDC, gate voltage VG, gate resistance Rg, load inductance L, and temperature TC. Furthermore, a method to enhance the dynamic avalanche reliability of the FS-IGBT under UIS by optimizing circuit parameters is proposed. In practical applications, reducing gate voltage, increasing load inductance, and lowering temperature can effectively improve the dynamic avalanche capability of the FS-IGBT.
Nucleation control for the growth of two-dimensional single crystals
Jinxia Bai, Chi Zhang, Fankai Zeng, Jinzong Kou, Jinhuan Wang, Xiaozhi Xu
, Available online  
doi: 10.1088/1674-4926/25030023

The unique structure and exceptional properties of two-dimensional (2D) materials offer significant potential for transformative advancements in semiconductor industry. Similar to the reliance on wafer-scale single-crystal ingots for silicon-based chips, practical applications of 2D materials at the chip level needs large-scale, high-quality production of 2D single crystals. Over the past two decades, the size of 2D single-crystals has been improved to wafer or meter scale, where the nucleation control during the growth process is particularly important. Therefore, it is essential to conduct a comprehensive review of nucleation control in 2D materials to gain fundamental insights into the growth of 2D single-crystal materials. This review mainly focuses on two aspects: controlling nucleation density to enable the growth from a single nucleus, and controlling nucleation position to achieve the unidirectionally aligned islands and subsequent seamless stitching. Finally, we provide an overview and forecast of the strategic pathways for emerging 2D materials.

The unique structure and exceptional properties of two-dimensional (2D) materials offer significant potential for transformative advancements in semiconductor industry. Similar to the reliance on wafer-scale single-crystal ingots for silicon-based chips, practical applications of 2D materials at the chip level needs large-scale, high-quality production of 2D single crystals. Over the past two decades, the size of 2D single-crystals has been improved to wafer or meter scale, where the nucleation control during the growth process is particularly important. Therefore, it is essential to conduct a comprehensive review of nucleation control in 2D materials to gain fundamental insights into the growth of 2D single-crystal materials. This review mainly focuses on two aspects: controlling nucleation density to enable the growth from a single nucleus, and controlling nucleation position to achieve the unidirectionally aligned islands and subsequent seamless stitching. Finally, we provide an overview and forecast of the strategic pathways for emerging 2D materials.
Jitter suppression scheme for detection pulses in high-speed sinusoidal gated single-photon detectors
Lianjun Jiang, Dongdong Li, Dawei Li, Yuqiang Fang, Ming Liu, Wei Jiang, Zhilin Xie, Guoqing Liu, Rui Ma, Yukang Zhao, Jian Sun, Lei Chang, Lin Yu, Shibiao Tang
, Available online  
doi: 10.1088/1674-4926/25030031

Quantum key distribution (QKD) achieves information-theoretic security based on quantum mechanics principles, where single-photon detectors (SPDs) serve as critical components. This study focuses on the sinusoidal gated SPDs widely used in high-speed QKD systems. We investigate the mechanisms underlying the rising-edge jitter in detection signals, identifying contributions from factors such as the temporal width of injected optical pulses, avalanche generation processes, avalanche signal extraction, and pulse discrimination. To address the issue of excessive jitter-induced bit errors, we propose a retiming scheme that utilizes coincidence signals synchronized with the sinusoidal gating signal. This approach effectively suppresses detection signal jitter and reduces the after-pulse probability of the detector. Experimental validation using a high-precision time-to-digital converter (TDC) demonstrates a significant reduction in the rising-edge jitter distribution after applying the suppression scheme. The proposed method features clear principles and straightforward engineering implementation, avoiding direct interference with the detector’s operational processes. The designed high-speed sinusoidal gated InGaAs/InP SPD operates at 1.25GHz, achieving a remarkable reduction in after-pulse probability from 10.7% (without jitter suppression) to 0.72%, thereby enhancing the overall performance of QKD systems.

Quantum key distribution (QKD) achieves information-theoretic security based on quantum mechanics principles, where single-photon detectors (SPDs) serve as critical components. This study focuses on the sinusoidal gated SPDs widely used in high-speed QKD systems. We investigate the mechanisms underlying the rising-edge jitter in detection signals, identifying contributions from factors such as the temporal width of injected optical pulses, avalanche generation processes, avalanche signal extraction, and pulse discrimination. To address the issue of excessive jitter-induced bit errors, we propose a retiming scheme that utilizes coincidence signals synchronized with the sinusoidal gating signal. This approach effectively suppresses detection signal jitter and reduces the after-pulse probability of the detector. Experimental validation using a high-precision time-to-digital converter (TDC) demonstrates a significant reduction in the rising-edge jitter distribution after applying the suppression scheme. The proposed method features clear principles and straightforward engineering implementation, avoiding direct interference with the detector’s operational processes. The designed high-speed sinusoidal gated InGaAs/InP SPD operates at 1.25GHz, achieving a remarkable reduction in after-pulse probability from 10.7% (without jitter suppression) to 0.72%, thereby enhancing the overall performance of QKD systems.
A RISC-V 32-bit microprocessor on two-dimensional semiconductor platform
Di Zhang, Yang Li
, Available online  
doi: 10.1088/1674-4926/25050016

A 2D/3D vision chip based on organic substrate 3D package
Siyuan Wei, Quanmin Chen, Jingyi Yu, Xuanzhe Xu, Yuxiao Wen, Runjiang Dou, Shuangming Yu, Guike Li, Kaiming Nie, Jie Cheng, Jiangtao Xu, Liyuan Liu, Nanjian Wu
, Available online  
doi: 10.1088/1674-4926/25010030

This paper describes a 2D/3D vision chip with integrated sensing and processing capabilities. The 2D/3D vision chip architecture includes a 2D/3D image sensor and a programmable visual processor. In this architecture, we design a novel on-chip processing flow with die-to-die image transmission and low-latency fixed-point image processing. The vision chip achieves real-time end-to-end processing of convolutional neural networks (CNNs) and conventional image processing algorithms. Furthermore, an end-to-end 2D/3D vision system is built to exhibit the capacity of the vision chip. The vision system achieves real-timing applications under 2D and 3D scenes, such as human face detection (processing delay 10.2 ms) and depth map reconstruction (processing delay 4.1 ms). The frame rate of image acquisition, image process, and result display is larger than 30 fps.

This paper describes a 2D/3D vision chip with integrated sensing and processing capabilities. The 2D/3D vision chip architecture includes a 2D/3D image sensor and a programmable visual processor. In this architecture, we design a novel on-chip processing flow with die-to-die image transmission and low-latency fixed-point image processing. The vision chip achieves real-time end-to-end processing of convolutional neural networks (CNNs) and conventional image processing algorithms. Furthermore, an end-to-end 2D/3D vision system is built to exhibit the capacity of the vision chip. The vision system achieves real-timing applications under 2D and 3D scenes, such as human face detection (processing delay 10.2 ms) and depth map reconstruction (processing delay 4.1 ms). The frame rate of image acquisition, image process, and result display is larger than 30 fps.
Facile construction of p-Si/n-SnO2 junction towards high performance self-powered UV photodetector
Xingyu Li, Li Tian, Jinshou Wang, Hui Liu
, Available online  
doi: 10.1088/1674-4926/24090048

Recently, self-powered ultraviolet photodetectors (UV PDs) based on SnO2 have gained increasing interest due to its feature of working continuously without the need for external power sources. Nevertheless, the production of the majority of these existing UV PDs necessitates additional manufacturing stages or intricate processes. In this work, we present a facile, cost-effective approach for the fabrication of a self-powered UV PD based on p-Si/n-SnO2 junction. The self-powered device was achieved simply by integrating a p-Si substrate with a n-type SnO2 microbelt, which was synthesized via the chemical vapor deposition (CVD) method. The high-quality feature, coupled with the belt-like shape of the SnO2 microbelt enables the favorable contact between the n-type SnO2 and p-type silicon. The built-in electric field created at the interface endows the self-powered performance of the device. The p-Si/n-SnO2 junction photodetector demonstrated a high responsivity (0.12 mA/W), high light/dark current ratio (>103), and rapid response speed at zero bias. This method offers a practical way to develop cost-effective and high-performance self-powered UV PDs.

Recently, self-powered ultraviolet photodetectors (UV PDs) based on SnO2 have gained increasing interest due to its feature of working continuously without the need for external power sources. Nevertheless, the production of the majority of these existing UV PDs necessitates additional manufacturing stages or intricate processes. In this work, we present a facile, cost-effective approach for the fabrication of a self-powered UV PD based on p-Si/n-SnO2 junction. The self-powered device was achieved simply by integrating a p-Si substrate with a n-type SnO2 microbelt, which was synthesized via the chemical vapor deposition (CVD) method. The high-quality feature, coupled with the belt-like shape of the SnO2 microbelt enables the favorable contact between the n-type SnO2 and p-type silicon. The built-in electric field created at the interface endows the self-powered performance of the device. The p-Si/n-SnO2 junction photodetector demonstrated a high responsivity (0.12 mA/W), high light/dark current ratio (>103), and rapid response speed at zero bias. This method offers a practical way to develop cost-effective and high-performance self-powered UV PDs.
Growth and optical properties of large-sized Co2+: ZnGa2O4 single crystal
Zhengyuan Li, Jiaqi Wei, Yiyuan Liu, Huihui Li, Yang Li, Zhitai Jia, Xutang Tao, Wenxiang Mu
, Available online  
doi: 10.1088/1674-4926/25010017

The transition of cobalt ions located at tetrahedral sites will produce strong absorption in the visible and near-infrared regions, and is expected to work in a passively Q-switched solid-state laser at the eye-safe wavelength of 1.5 µm. In this study, Co2+ ions were introduced into the wide bandgap semiconductor material ZnGa2O4, and large-sized and high-quality Co2+-doped ZnGa2O4 crystals with a volume of about 20 cm3 were grown using the vertical gradient freeze (VGF) method. Crystal structure and optical properties were analyzed using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and absorption spectroscopy. XRD results show that the Co2+-doped ZnGa2O4 crystal has a pure spinel phase without impurity phases and the rocking curve full width at half maximum (FWHM) is only 58 arcsec. The concentration of Co2+ in Co2+-doped ZnGa2O4 crystals was determined to be 0.2 at.% by the energy dispersive X-ray spectroscopy. The optical band gap of Co2+-doped ZnGa2O4 crystals is 4.44 eV. The optical absorption spectrum for Co2+-doped ZnGa2O4 reveals a prominent visible absorption band within 550−670 nm and a wide absorption band spanning from 1100 to 1700 nm. This suggests that the Co2+ ions have substituted the Zn2+ ions, which are typically tetrahedrally coordinated, within the lattice structure of ZnGa2O4. The visible region's absorption peak and the near-infrared broad absorption band are ascribed to the 4A2(4F) → 4T1(4P) and 4A2(4F) →4T1(4F) transitions, respectively. The optimal ground state absorption cross section was determined to be 3.07 × 10−19 cm2 in ZnGa2O4, a value that is comparatively large within the context of similar materials. This finding suggests that ZnGa2O4 is a promising candidate for use in near-infrared passive Q-switched solid-state lasers.

The transition of cobalt ions located at tetrahedral sites will produce strong absorption in the visible and near-infrared regions, and is expected to work in a passively Q-switched solid-state laser at the eye-safe wavelength of 1.5 µm. In this study, Co2+ ions were introduced into the wide bandgap semiconductor material ZnGa2O4, and large-sized and high-quality Co2+-doped ZnGa2O4 crystals with a volume of about 20 cm3 were grown using the vertical gradient freeze (VGF) method. Crystal structure and optical properties were analyzed using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and absorption spectroscopy. XRD results show that the Co2+-doped ZnGa2O4 crystal has a pure spinel phase without impurity phases and the rocking curve full width at half maximum (FWHM) is only 58 arcsec. The concentration of Co2+ in Co2+-doped ZnGa2O4 crystals was determined to be 0.2 at.% by the energy dispersive X-ray spectroscopy. The optical band gap of Co2+-doped ZnGa2O4 crystals is 4.44 eV. The optical absorption spectrum for Co2+-doped ZnGa2O4 reveals a prominent visible absorption band within 550−670 nm and a wide absorption band spanning from 1100 to 1700 nm. This suggests that the Co2+ ions have substituted the Zn2+ ions, which are typically tetrahedrally coordinated, within the lattice structure of ZnGa2O4. The visible region's absorption peak and the near-infrared broad absorption band are ascribed to the 4A2(4F) → 4T1(4P) and 4A2(4F) →4T1(4F) transitions, respectively. The optimal ground state absorption cross section was determined to be 3.07 × 10−19 cm2 in ZnGa2O4, a value that is comparatively large within the context of similar materials. This finding suggests that ZnGa2O4 is a promising candidate for use in near-infrared passive Q-switched solid-state lasers.
Boosting photoelectrochemical performance on α-Ga2O3 nanowire arrays by indium cation doping for self-powered ultraviolet detection
Junjun Xue, Jiyuan Huang, Kehan Li, Ping Liu, Yan Gu, Ting Zhi, Yan Dong, Jin Wang
, Available online  
doi: 10.1088/1674-4926/25020024

Low power consumption, high responsivity, and self-powering are key objectives for photoelectrochemical ultraviolet detectors. In this research, In-doped α-Ga2O3 nanowire arrays were fabricated on FTO substrates through a hydrothermal approach, with subsequent thermal annealing. These arrays were then used as photoanodes to construct a ultraviolet (UV) photodetector. In doping reduced the bandgap of α-Ga2O3, enhancing its absorption of UV light. Consequently, the In-doped α-Ga2O3 nanowire arrays exhibited excellent light detection performance. When irradiated by 255 nm deep ultraviolet light, they obtained a responsivity of 38.85 mA/W. Moreover, the detector's response and recovery times are 13 and 8 ms, respectively. The In-doped α-Ga2O3 nanowire arrays exhibit a responsivity that is about three-fold higher than the undoped one. Due to its superior responsivity, the In-doped device was used to develop a photoelectric imaging system. This study demonstrates that doping α-Ga2O3 nanowire with indium is a potent approach for optimizing their photoelectrochemical performance, which also has significant potential for optoelectronic applications.

Low power consumption, high responsivity, and self-powering are key objectives for photoelectrochemical ultraviolet detectors. In this research, In-doped α-Ga2O3 nanowire arrays were fabricated on FTO substrates through a hydrothermal approach, with subsequent thermal annealing. These arrays were then used as photoanodes to construct a ultraviolet (UV) photodetector. In doping reduced the bandgap of α-Ga2O3, enhancing its absorption of UV light. Consequently, the In-doped α-Ga2O3 nanowire arrays exhibited excellent light detection performance. When irradiated by 255 nm deep ultraviolet light, they obtained a responsivity of 38.85 mA/W. Moreover, the detector's response and recovery times are 13 and 8 ms, respectively. The In-doped α-Ga2O3 nanowire arrays exhibit a responsivity that is about three-fold higher than the undoped one. Due to its superior responsivity, the In-doped device was used to develop a photoelectric imaging system. This study demonstrates that doping α-Ga2O3 nanowire with indium is a potent approach for optimizing their photoelectrochemical performance, which also has significant potential for optoelectronic applications.
AlGaN/GaN-based SBDs grown on silicon substrates with trenched n+-GaN cap layer and local passivation layer to improve BFOM and dynamic properties
Zhizhong Wang, Jingting He, Fuping Huang, Xuchen Gao, Kangkai Tian, Chunshuang Chu, Yonghui Zhang, Shuting Cai, Xiaojuan Sun, Dabing Li, Xiao Wei Sun, Zi-Hui Zhang
, Available online  
doi: 10.1088/1674-4926/25010024

In this work, we design and fabricate AlGaN/GaN-based Schottky barrier diodes (SBDs) on a silicon substrate with a trenched n+-GaN cap layer. With the developed physical models, we find that the n+-GaN cap layer provides more electrons into the AlGaN/GaN channel, which is further confirmed experimentally. When compared with the reference device, this increases the two-dimensional electron gas (2DEG) density by two times and leads to a reduced specific ON-resistance (Ron,sp) of ~2.4 mΩ·cm2. We also adopt the trenched n+-GaN structure such that partial of the n+-GaN is removed by using dry etching process to eliminate the surface electrical conduction when the device is set in the off-state. To suppress the surface defects that are caused by the dry etching process, we also deposit Si3N4 layer prior to the deposition of field plate (FP), and we obtain a reduced leakage current of ~8 × 10−5 A·cm−2 and breakdown voltage (BV) of 876 V. The Baliga’s figure of merit (BFOM) for the proposed structure is increased to ~319 MW·cm−2. Our investigations also find that the pre-deposited Si3N4 layer helps suppress the electron capture and transport processes, which enables the reduced dynamic Ron,sp.

In this work, we design and fabricate AlGaN/GaN-based Schottky barrier diodes (SBDs) on a silicon substrate with a trenched n+-GaN cap layer. With the developed physical models, we find that the n+-GaN cap layer provides more electrons into the AlGaN/GaN channel, which is further confirmed experimentally. When compared with the reference device, this increases the two-dimensional electron gas (2DEG) density by two times and leads to a reduced specific ON-resistance (Ron,sp) of ~2.4 mΩ·cm2. We also adopt the trenched n+-GaN structure such that partial of the n+-GaN is removed by using dry etching process to eliminate the surface electrical conduction when the device is set in the off-state. To suppress the surface defects that are caused by the dry etching process, we also deposit Si3N4 layer prior to the deposition of field plate (FP), and we obtain a reduced leakage current of ~8 × 10−5 A·cm−2 and breakdown voltage (BV) of 876 V. The Baliga’s figure of merit (BFOM) for the proposed structure is increased to ~319 MW·cm−2. Our investigations also find that the pre-deposited Si3N4 layer helps suppress the electron capture and transport processes, which enables the reduced dynamic Ron,sp.
A simple and effective carrier lifetime characterization for semiconductor thin films
Bao Quy Le, Tuan Nguyen Van, Dat Tran Quang, Vi Le Dinh, Thin Pham Van, Nguyen Cuc Thi Kim
, Available online  
doi: 10.1088/1674-4926/24090005

Minority carrier lifetimes τ are a fundamental parameter in semiconductor devices, representing the average time it takes for excess minority carriers to recombine. This characteristic is crucial for understanding and optimizing the performance of semiconductor materials, as it directly influences charge carrier dynamics and overall device efficiency. This work presents a development of PbS thin film deposited by thermal evaporation, at which the PbS thin film was further employed for structural, optical properties, and τ. Especially, the PbS film is probed with an in-house setup for identifying the τ. The procedure is to subject the PbS thin film with a flashlight from a light source with a middle rotating frequency. The derived τ in the in-house characterization setup agrees well with the value from the higher cost characterizing approach of photoluminescence. Therefore, the in-house setup provides additional tools for identifying the τ values for semiconductor devices.

Minority carrier lifetimes τ are a fundamental parameter in semiconductor devices, representing the average time it takes for excess minority carriers to recombine. This characteristic is crucial for understanding and optimizing the performance of semiconductor materials, as it directly influences charge carrier dynamics and overall device efficiency. This work presents a development of PbS thin film deposited by thermal evaporation, at which the PbS thin film was further employed for structural, optical properties, and τ. Especially, the PbS film is probed with an in-house setup for identifying the τ. The procedure is to subject the PbS thin film with a flashlight from a light source with a middle rotating frequency. The derived τ in the in-house characterization setup agrees well with the value from the higher cost characterizing approach of photoluminescence. Therefore, the in-house setup provides additional tools for identifying the τ values for semiconductor devices.
Review on three-dimensional graphene: synthesis and joint photoelectric regulation in photodetectors
Bingkun Wang, Jinqiu Zhang, Huijuan Wu, Fanghao Zhu, Shanshui Lian, Genqiang Cao, Hui Ma, Xurui Hu, Li Zheng, Gang Wang
, Available online  
doi: 10.1088/1674-4926/25010015

Graphene has garnered significant attention in photodetection due to its exceptional optical, electrical, mechanical, and thermal properties. However, the practical application of two-dimensional (2D) graphene in optoelectronic fields is limited by its weak light absorption (only 2.3%) and zero bandgap characteristics. Increasing light absorption is a critical scientific challenge for developing high-performance graphene-based photodetectors. Three-dimensional (3D) graphene comprises vertically grown stacked 2D-graphene layers and features a distinctive porous structure. Unlike 2D-graphene, 3D-graphene offers a larger specific surface area, improved electrochemical activity, and high chemical stability, making it a promising material for optoelectronic detection. Importantly, 3D-graphene has an optical microcavity structure that enhances light absorption through interaction with incoming light. This paper systematically reviews and analyzes the current research status and challenges of 3D-graphene-based photodetectors, aiming to explore feasible development paths for these devices and promote their industrial application.

Graphene has garnered significant attention in photodetection due to its exceptional optical, electrical, mechanical, and thermal properties. However, the practical application of two-dimensional (2D) graphene in optoelectronic fields is limited by its weak light absorption (only 2.3%) and zero bandgap characteristics. Increasing light absorption is a critical scientific challenge for developing high-performance graphene-based photodetectors. Three-dimensional (3D) graphene comprises vertically grown stacked 2D-graphene layers and features a distinctive porous structure. Unlike 2D-graphene, 3D-graphene offers a larger specific surface area, improved electrochemical activity, and high chemical stability, making it a promising material for optoelectronic detection. Importantly, 3D-graphene has an optical microcavity structure that enhances light absorption through interaction with incoming light. This paper systematically reviews and analyzes the current research status and challenges of 3D-graphene-based photodetectors, aiming to explore feasible development paths for these devices and promote their industrial application.
Improving electrical performance and fringe effect in p-type SnOx thin film transistors via Ta incorporation
Yu Song, Runtong Guo, Ruohao Hong, Rui He, Xuming Zou, Benjamin Iñiguez, Denis Flandre, Lei Liao, Guoli Li
, Available online  
doi: 10.1088/1674-4926/25010031

In this work, the incorporation of tantalum (Ta) into p-type metal-oxide (SnOx) semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors (TFTs). The Ta-doped SnOx (SnOx:Ta) film is deposited by radio-frequency (RF) magnetron sputtering with a Sn:Ta (3at.%) target and thermally annealed at 270 °C for 30 min. Here, we observe that the SnOx:Ta film presents increased crystallinity, reduced defect density (3.25 × 1012 cm−2·eV−1), and widened bandgap (1.98 eV), in comparison with the undoped SnOx film. As a result, the SnOx:Ta TFTs exhibit a lower off-state current (Ioff), an improved on/off current ratio (2.17 × 104), a remarkably decreased subthreshold swing (SS) by 41%, and enhanced device stability. Additionally, by introducing Ta dopants, the fringe effect as well as the impact of channel width-to-length ratio (W/L) on electrical performances of the p-type oxide TFTs can be effectively suppressed. These results shall contribute to further exploration and development of p-type SnOx TFTs.

In this work, the incorporation of tantalum (Ta) into p-type metal-oxide (SnOx) semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors (TFTs). The Ta-doped SnOx (SnOx:Ta) film is deposited by radio-frequency (RF) magnetron sputtering with a Sn:Ta (3at.%) target and thermally annealed at 270 °C for 30 min. Here, we observe that the SnOx:Ta film presents increased crystallinity, reduced defect density (3.25 × 1012 cm−2·eV−1), and widened bandgap (1.98 eV), in comparison with the undoped SnOx film. As a result, the SnOx:Ta TFTs exhibit a lower off-state current (Ioff), an improved on/off current ratio (2.17 × 104), a remarkably decreased subthreshold swing (SS) by 41%, and enhanced device stability. Additionally, by introducing Ta dopants, the fringe effect as well as the impact of channel width-to-length ratio (W/L) on electrical performances of the p-type oxide TFTs can be effectively suppressed. These results shall contribute to further exploration and development of p-type SnOx TFTs.
Trends and emerging techniques in isolated power converters
Lin Cheng, Dongfang Pan
, Available online  
doi: 10.1088/1674-4926/25040037

A semiconductor radiation dosimeter fabricated in 8-inch process
Jun Huang, Bojin Pan, Hang bao, Qiuyue Huo, Renxiong Li, Qi Ding, Yutuo Guo, Yu Wang, Kunqin He, Yaxin Liu, Ziyi Zeng, Ning Ning, Lulu Peng
, Available online  
doi: 10.1088/1674-4926/24120027

The RADFET radiation dosimeter is a type of radiation detector based on the total dose effects of the PMOS transistor. The RADFET chip was fabricated in CUMEC 8-inch process with a six-layer photomask. The chip including two identical PMOS transistors, occupies a size of 610 µm×610 µm. Each PMOS has a W/L ratio of 300 µm/50 µm, and a 400 nm thick gate oxide, which is formed by a dry-wet-dry oxygen process. The wet oxygen-formed gate oxide with more traps can capture more holes during irradiation, thus significantly changing the PMOS threshold voltage. Pre-irradiation measurement results from ten test chips show that the initial average voltage of the PMOS is 1.961 V with a dispersion of 5.7%. The irradiation experiment is conducted in a cobalt source facility with a dose rate of 50 rad(Si)/s. During irradiation, a constant current source circuit of 10 µA was connected to monitoring the shift in threshold voltage under different total dose. When the total dose is 100 krad(Si), the shift in threshold voltage was approximately 1.37 V, which demonstrates that an excellent radiation function was achieved.

The RADFET radiation dosimeter is a type of radiation detector based on the total dose effects of the PMOS transistor. The RADFET chip was fabricated in CUMEC 8-inch process with a six-layer photomask. The chip including two identical PMOS transistors, occupies a size of 610 µm×610 µm. Each PMOS has a W/L ratio of 300 µm/50 µm, and a 400 nm thick gate oxide, which is formed by a dry-wet-dry oxygen process. The wet oxygen-formed gate oxide with more traps can capture more holes during irradiation, thus significantly changing the PMOS threshold voltage. Pre-irradiation measurement results from ten test chips show that the initial average voltage of the PMOS is 1.961 V with a dispersion of 5.7%. The irradiation experiment is conducted in a cobalt source facility with a dose rate of 50 rad(Si)/s. During irradiation, a constant current source circuit of 10 µA was connected to monitoring the shift in threshold voltage under different total dose. When the total dose is 100 krad(Si), the shift in threshold voltage was approximately 1.37 V, which demonstrates that an excellent radiation function was achieved.
Reducing specific contact resistivity of V/Al/Ti/Au n-electrode on n-AlGaN with Al content over 80% for far-UVC LEDs
Jiale Peng, Ke Jiang, Shanli Zhang, Jianwei Ben, Kexi Liu, Ziyue Qin, Ruihua Chen, Chunyue Zhang, Shunpeng Lv, Xiaojuan Sun, Dabing Li
, Available online  
doi: 10.1088/1674-4926/25010026

AlGaN-based LEDs with peak wavelength below 240 nm (far-UVC) pose no significant harm to human health, thus highlighting their broader application potential. While, there is a significant Schottky barrier between the n-electrode and Al-rich n-AlGaN, adversely impeding electron injection and resulting in considerable heat generation. Here, we fabricate V-based electrodes of V/Al/Ti/Au on n-AlGaN with Al content over 80% and investigate the relationship between the metal diffusion and contact properties during the high-temperature annealing process. Experiments reveal that decreasing V thickness in the electrode promotes the diffusion of Al towards the surface of n-AlGaN, which facilitates the formation of VN and thus the increase of local electron concentration, resulting in lower specific contact resistivity. Then, increasing the Al thickness inhibits the diffusion of Au to the n-AlGaN surface, suppressing the rise of Schottky barrier. Experimentally, an optimized n-electrode of V(10 nm)/Al(240 nm)/Ti(40 nm)/Au(50 nm) on n-Al0.81Ga0.19N is obtained, realizing an optimal specific contact resistivity of 7.30 × 10−4 Ω·cm2. Based on the optimal n-electrode preparation scheme for Al-rich n-AlGaN, the work voltage of a far-UVC LED with peak wavelength of 233.5 nm is effectively reduced.

AlGaN-based LEDs with peak wavelength below 240 nm (far-UVC) pose no significant harm to human health, thus highlighting their broader application potential. While, there is a significant Schottky barrier between the n-electrode and Al-rich n-AlGaN, adversely impeding electron injection and resulting in considerable heat generation. Here, we fabricate V-based electrodes of V/Al/Ti/Au on n-AlGaN with Al content over 80% and investigate the relationship between the metal diffusion and contact properties during the high-temperature annealing process. Experiments reveal that decreasing V thickness in the electrode promotes the diffusion of Al towards the surface of n-AlGaN, which facilitates the formation of VN and thus the increase of local electron concentration, resulting in lower specific contact resistivity. Then, increasing the Al thickness inhibits the diffusion of Au to the n-AlGaN surface, suppressing the rise of Schottky barrier. Experimentally, an optimized n-electrode of V(10 nm)/Al(240 nm)/Ti(40 nm)/Au(50 nm) on n-Al0.81Ga0.19N is obtained, realizing an optimal specific contact resistivity of 7.30 × 10−4 Ω·cm2. Based on the optimal n-electrode preparation scheme for Al-rich n-AlGaN, the work voltage of a far-UVC LED with peak wavelength of 233.5 nm is effectively reduced.
A 128 × 128 monolithic spike-based hybrid-vision sensor with 0.96 Geps and 117 kfps
Huanhui Zhang, Chi Zhang, Xu Yang, Zhe Wang, Cong Shi, Runjiang Dou, Shuangming Yu, Jian Liu, Nanjian Wu, Peng Feng, Liyuan Liu
, Available online  
doi: 10.1088/1674-4926/25020010

The event-based vision sensor (EVS), which can generate efficient spiking data streams by exclusively detecting motion, exemplifies neuromorphic vision methodologies. Generally, its inherent lack of texture features limits effectiveness in complex vision processing tasks, necessitating supplementary visual information. However, to date, no event-based hybrid vision solution has been developed that preserves the characteristics of complete spike data streams to support synchronous computation architectures based on spiking neural network (SNN). In this paper, we present a novel spike-based sensor with digitized pixels, which integrates the event detection structure with the pulse frequency modulation (PFM) circuit. This design enables the simultaneous output of spiking data that encodes both temporal changes and texture information. Fabricated in 180 nm process, the proposed sensor achieves a resolution of 128 × 128, a maximum event rate of 960 Meps, a grayscale framerate of 117.1 kfps, and a measured power consumption of 60.1 mW, which is suited for high-speed, low-latency, edge SNN-based vision computing systems.

The event-based vision sensor (EVS), which can generate efficient spiking data streams by exclusively detecting motion, exemplifies neuromorphic vision methodologies. Generally, its inherent lack of texture features limits effectiveness in complex vision processing tasks, necessitating supplementary visual information. However, to date, no event-based hybrid vision solution has been developed that preserves the characteristics of complete spike data streams to support synchronous computation architectures based on spiking neural network (SNN). In this paper, we present a novel spike-based sensor with digitized pixels, which integrates the event detection structure with the pulse frequency modulation (PFM) circuit. This design enables the simultaneous output of spiking data that encodes both temporal changes and texture information. Fabricated in 180 nm process, the proposed sensor achieves a resolution of 128 × 128, a maximum event rate of 960 Meps, a grayscale framerate of 117.1 kfps, and a measured power consumption of 60.1 mW, which is suited for high-speed, low-latency, edge SNN-based vision computing systems.
Investigating the doping performance of an ionic dopant for organic semiconductors and thermoelectric applications
Jing Guo, Yaru Feng, Jinjun Zhang, Jing Zhang, Ping−An Chen, Huan Wei, Xincan Qiu, Yu Liu, Jiangnan Xia, Huajie Chen, Yugang Bai, Lang Jiang, Yuanyuan Hu
, Available online  
doi: 10.1088/1674-4926/25010027

Doping plays a pivotal role in enhancing the performance of organic semiconductors (OSCs) for advanced optoelectronic and thermoelectric applications. In this study, we systematically investigated the doping performance and applicability of the ionic dopant 4-isopropyl-4′-methyldiphenyliodonium tetrakis(penta-fluorophenyl-borate) (DPI-TPFB) as a p-dopant for OSCs. Using the p-type OSC PBBT-2T as a model system, we demonstrated that DPI-TPFB shows significant doping effect, as confirmed by ESR spectra, UV−vis−NIR absorption, and work function analysis, and enhances the electronic conductivity of PBBT-2T films by over four orders of magnitude. Furthermore, DPI-TPFB exhibited broad doping applicability, effectively doping various p-type OSCs and even imparting p-type characteristics to the n-type OSC N2200, transforming its intrinsic n-type behavior into p-type. The application of DPI-TPFB-doped PBBT-2T films in organic thermoelectric devices (OTEs) was also explored, achieving a power factor of approximately 10 μW∙m−1∙K−2. These findings highlight the potential of DPI-TPFB as a versatile and efficient dopant for integration into organic optoelectronic and thermoelectric devices.

Doping plays a pivotal role in enhancing the performance of organic semiconductors (OSCs) for advanced optoelectronic and thermoelectric applications. In this study, we systematically investigated the doping performance and applicability of the ionic dopant 4-isopropyl-4′-methyldiphenyliodonium tetrakis(penta-fluorophenyl-borate) (DPI-TPFB) as a p-dopant for OSCs. Using the p-type OSC PBBT-2T as a model system, we demonstrated that DPI-TPFB shows significant doping effect, as confirmed by ESR spectra, UV−vis−NIR absorption, and work function analysis, and enhances the electronic conductivity of PBBT-2T films by over four orders of magnitude. Furthermore, DPI-TPFB exhibited broad doping applicability, effectively doping various p-type OSCs and even imparting p-type characteristics to the n-type OSC N2200, transforming its intrinsic n-type behavior into p-type. The application of DPI-TPFB-doped PBBT-2T films in organic thermoelectric devices (OTEs) was also explored, achieving a power factor of approximately 10 μW∙m−1∙K−2. These findings highlight the potential of DPI-TPFB as a versatile and efficient dopant for integration into organic optoelectronic and thermoelectric devices.
Self-assembled flexible Ti3C2Tx MXene-based thermally chargeable supercapacitor
Lifeng Wu, La Li, Guozhen Shen
, Available online  
doi: 10.1088/1674-4926/25030009

Thermally chargeable supercapacitors (TCSCs) have unique advantages in the collection, conversion, and storage of thermal energy, contributing to the development of new strategies for thermal energy utilization. 2D MXene materials are predicted to be highly promising new thermoelectric materials. Here, we report a self-assembled flexible Ti3C2Tx MXene-based TCSC device, using prepared Ti3C2Tx MXene as the capacitor electrode and a NaClO4/PEO gel as the electrolyte. We also explore the working mechanism of the TCSCs. The fabricated Ti3C2Tx-based TCSCs exhibit an excellent Seebeck coefficient of 11.8 mV∙K−1 on average and maintain good cycling stability under various temperature differences. Demonstrations of multiple practical applications show that Ti3C2Tx MXene-based TCSC devices are excellent candidates for self-powered integrated electronic devices.

Thermally chargeable supercapacitors (TCSCs) have unique advantages in the collection, conversion, and storage of thermal energy, contributing to the development of new strategies for thermal energy utilization. 2D MXene materials are predicted to be highly promising new thermoelectric materials. Here, we report a self-assembled flexible Ti3C2Tx MXene-based TCSC device, using prepared Ti3C2Tx MXene as the capacitor electrode and a NaClO4/PEO gel as the electrolyte. We also explore the working mechanism of the TCSCs. The fabricated Ti3C2Tx-based TCSCs exhibit an excellent Seebeck coefficient of 11.8 mV∙K−1 on average and maintain good cycling stability under various temperature differences. Demonstrations of multiple practical applications show that Ti3C2Tx MXene-based TCSC devices are excellent candidates for self-powered integrated electronic devices.
Multi-chip multi-phase DC−DC converters for AI power: a ring, a chain, or a net, independent or master-slave?
Yan Lu, Zhiguo Tong, Jiacheng Yang, Zhewen Yu, Mo Huang, Xiangyu Mao
, Available online  
doi: 10.1088/1674-4926/25040033

Robotic computing system and embodied AI evolution: an algorithm-hardware co-design perspective
Longke Yan, Xin Zhao, Bohan Yang, Yongkun Wu, Guangnan Dai, Jiancong Li, Chi-Ying Tsui, Kwang-Ting Cheng, Yihan Zhang, Fengbin Tu
, Available online  
doi: 10.1088/1674-4926/25020034

Robotic computing systems play an important role in enabling intelligent robotic tasks through intelligent algorithms and supporting hardware. In recent years, the evolution of robotic algorithms indicates a roadmap from traditional robotics to hierarchical and end-to-end models. This algorithmic advancement poses a critical challenge in achieving balanced system-wide performance. Therefore, algorithm-hardware co-design has emerged as the primary methodology, which analyzes algorithm behaviors on hardware to identify common computational properties. These properties can motivate algorithm optimization to reduce computational complexity and hardware innovation from architecture to circuit for high performance and high energy efficiency. We then reviewed recent works on robotic and embodied AI algorithms and computing hardware to demonstrate this algorithm-hardware co-design methodology. In the end, we discuss future research opportunities by answering two questions: (1) how to adapt the computing platforms to the rapid evolution of embodied AI algorithms, and (2) how to transform the potential of emerging hardware innovations into end-to-end inference improvements.

Robotic computing systems play an important role in enabling intelligent robotic tasks through intelligent algorithms and supporting hardware. In recent years, the evolution of robotic algorithms indicates a roadmap from traditional robotics to hierarchical and end-to-end models. This algorithmic advancement poses a critical challenge in achieving balanced system-wide performance. Therefore, algorithm-hardware co-design has emerged as the primary methodology, which analyzes algorithm behaviors on hardware to identify common computational properties. These properties can motivate algorithm optimization to reduce computational complexity and hardware innovation from architecture to circuit for high performance and high energy efficiency. We then reviewed recent works on robotic and embodied AI algorithms and computing hardware to demonstrate this algorithm-hardware co-design methodology. In the end, we discuss future research opportunities by answering two questions: (1) how to adapt the computing platforms to the rapid evolution of embodied AI algorithms, and (2) how to transform the potential of emerging hardware innovations into end-to-end inference improvements.
A 0.1−5.1 GHz high-gain LNA with inductorless composite resistor−capacitor feedback structure based on a 0.25 μm SiGe BiCMOS process
Zhouhao Zhao, Qian Chen, Yixing Lu, Haigang Feng
, Available online  
doi: 10.1088/1674-4926/24110028

In this paper, a high-gain inductorless LNA (low-noise amplifier) compatible with multiple communication protocols from 0.1 to 5.1 GHz is proposed. A composite resistor−capacitor feedback structure is employed to achieve a wide bandwidth matching range and good gain flatness. A second stage with a Darlington pair is used to increase the overall gain of the amplifier, while the gain of the first stage is reduced to reduce the overall noise. The amplifier is based on a 0.25 μm SiGe BiCMOS process, and thanks to the inductorless circuit structure, the core circuit area is only 0.03 mm2. Test results show that the lowest noise figure (NF) in the operating band is 1.99 dB, the power gain reaches 29.7 dB, the S11 and S22 are less than −10 dB, the S12 is less than −30 dB, the IIP3 is 0.81dBm, and the OP1dB is 10.27 dBm. The operating current is 31.18 mA at 3.8 V supply.

In this paper, a high-gain inductorless LNA (low-noise amplifier) compatible with multiple communication protocols from 0.1 to 5.1 GHz is proposed. A composite resistor−capacitor feedback structure is employed to achieve a wide bandwidth matching range and good gain flatness. A second stage with a Darlington pair is used to increase the overall gain of the amplifier, while the gain of the first stage is reduced to reduce the overall noise. The amplifier is based on a 0.25 μm SiGe BiCMOS process, and thanks to the inductorless circuit structure, the core circuit area is only 0.03 mm2. Test results show that the lowest noise figure (NF) in the operating band is 1.99 dB, the power gain reaches 29.7 dB, the S11 and S22 are less than −10 dB, the S12 is less than −30 dB, the IIP3 is 0.81dBm, and the OP1dB is 10.27 dBm. The operating current is 31.18 mA at 3.8 V supply.
Topological materials-based photodetectors from the infrared to terahertz range
Zhaowen Bao, Yiming Wang, Kaixuan Zhang, Yingdong Wei, Xiaokai Pan, Zhen Hu, Shiqi Lan, Yichong Zhang, Xiaoyun Wang, Huichuan Fan, Hongfei Wu, Lei Yang, Zhiyuan Zhou, Xin Sun, Yulu Chen, Lin Wang
, Available online  
doi: 10.1088/1674-4926/25010010

Infrared and terahertz waves constitute pivotal bands within the electromagnetic spectrum, distinguished by their robust penetration capabilities and non-ionizing nature. These wavebands offer the potential for achieving high-resolution and non-destructive detection methodologies, thereby possessing considerable research significance across diverse domains including communication technologies, biomedical applications, and security screening systems. Two-dimensional materials, owing to their distinctive optoelectronic attributes, have found widespread application in photodetection endeavors. Nonetheless, their efficacy diminishes when tasked with detecting lower photon energies. Furthermore, as the landscape of device integration evolves, two-dimensional materials struggle to align with the stringent demands for device superior performance. Topological materials, with their topologically protected electronic states and non-trivial topological invariants, exhibit quantum anomalous Hall effects and ultra-high carrier mobility, providing a new approach for seeking photosensitive materials for infrared and terahertz photodetectors. This article introduces various types of topological materials and their properties, followed by an explanation of the detection mechanism and performance parameters of photodetectors. Finally, it summarizes the current research status of near-infrared to far-infrared photodetectors and terahertz photodetectors based on topological materials, discussing the challenges faced and future prospects in their development.

Infrared and terahertz waves constitute pivotal bands within the electromagnetic spectrum, distinguished by their robust penetration capabilities and non-ionizing nature. These wavebands offer the potential for achieving high-resolution and non-destructive detection methodologies, thereby possessing considerable research significance across diverse domains including communication technologies, biomedical applications, and security screening systems. Two-dimensional materials, owing to their distinctive optoelectronic attributes, have found widespread application in photodetection endeavors. Nonetheless, their efficacy diminishes when tasked with detecting lower photon energies. Furthermore, as the landscape of device integration evolves, two-dimensional materials struggle to align with the stringent demands for device superior performance. Topological materials, with their topologically protected electronic states and non-trivial topological invariants, exhibit quantum anomalous Hall effects and ultra-high carrier mobility, providing a new approach for seeking photosensitive materials for infrared and terahertz photodetectors. This article introduces various types of topological materials and their properties, followed by an explanation of the detection mechanism and performance parameters of photodetectors. Finally, it summarizes the current research status of near-infrared to far-infrared photodetectors and terahertz photodetectors based on topological materials, discussing the challenges faced and future prospects in their development.
Band alignment of SnO/β-Ga2O3 heterojunction and its electrical properties for power device application
Xia Wu, Chenyang Huang, Xiuxing Xu, Jun Wang, Xinwang Yao, Yanfang Liu, Xiujuan Wang, Chunyan Wu, Linbao Luo
, Available online  
doi: 10.1088/1674-4926/25020008

In this study, we present the fabrication of vertical SnO/β-Ga2O3 heterojunction diode (HJD) via radio frequency (RF) reactive magnetron sputtering. The valence and conduction band offsets between β-Ga2O3 and SnO are determined to be 2.65 and 0.75 eV, respectively, through X-ray photoelectron spectroscopy, showing a type-II band alignment. Compared to its Schottky barrier diode (SBD) counterpart, the HJD presents a comparable specific ON-resistances (Ron,sp) of 2.8 mΩ·cm² and lower reverse leakage current (IR), leading to an enhanced reverse blocking characteristics with breakdown voltage (BV) of 1675 V and power figure of merit (PFOM) of 1.0 GW/cm². This demonstrates the high quality of the SnO/β-Ga2O3 heterojunction interface. Silvaco TCAD simulation further reveals that electric field crowding at the edge of anode for the SBD was greatly depressed by the introduction of SnO film, revealing the potential application of SnO/β-Ga2O3 heterojunction in the future β-Ga2O3-based power devices.

In this study, we present the fabrication of vertical SnO/β-Ga2O3 heterojunction diode (HJD) via radio frequency (RF) reactive magnetron sputtering. The valence and conduction band offsets between β-Ga2O3 and SnO are determined to be 2.65 and 0.75 eV, respectively, through X-ray photoelectron spectroscopy, showing a type-II band alignment. Compared to its Schottky barrier diode (SBD) counterpart, the HJD presents a comparable specific ON-resistances (Ron,sp) of 2.8 mΩ·cm² and lower reverse leakage current (IR), leading to an enhanced reverse blocking characteristics with breakdown voltage (BV) of 1675 V and power figure of merit (PFOM) of 1.0 GW/cm². This demonstrates the high quality of the SnO/β-Ga2O3 heterojunction interface. Silvaco TCAD simulation further reveals that electric field crowding at the edge of anode for the SBD was greatly depressed by the introduction of SnO film, revealing the potential application of SnO/β-Ga2O3 heterojunction in the future β-Ga2O3-based power devices.
Effect of grain size on the resistivity of polycrystalline 3C-SiC
Guo Li, Lei Ge, Mingsheng Xu, Jisheng Han, Xiangang Xu
, Available online  
doi: 10.1088/1674-4926/25020018

Silicon carbide offers distinct advantages in the field of power electronic devices. However, manufacturing processes remain a significant barrier to its widespread adoption. Polycrystalline SiC is less expensive and easier to produce than single crystal. But stabilizing and controlling its performance are critical challenges that must be addressed urgently. Due to its material properties and excellent performance in applications, 3C-SiC is gaining increasing attention in research. This article presents the electrical and material properties of a series of polycrystalline 3C-SiC samples and investigates their interrelationship. The samples were examined using TEM, which confirmed their polycrystalline structure. Combined with XRD and Raman spectroscopy, the grain orientations within the samples were analyzed, and the presence of stress was verified. EBSD was employed to statistically examine the grain structure and size across samples. For samples with similar doping levels, grain size is the most influential factor in determining electrical characteristics. Further EBSD measurements reveal the relationship between resistivity and grain size as log(ρ) = −1.93 + 8.67/d. These findings provide a foundation for the quantitative control and application of polycrystalline 3C-SiC. This work offers theoretical evidence for optimizing the performance tuning of 3C-SiC ceramics and enhancing their effectiveness in electronic applications.

Silicon carbide offers distinct advantages in the field of power electronic devices. However, manufacturing processes remain a significant barrier to its widespread adoption. Polycrystalline SiC is less expensive and easier to produce than single crystal. But stabilizing and controlling its performance are critical challenges that must be addressed urgently. Due to its material properties and excellent performance in applications, 3C-SiC is gaining increasing attention in research. This article presents the electrical and material properties of a series of polycrystalline 3C-SiC samples and investigates their interrelationship. The samples were examined using TEM, which confirmed their polycrystalline structure. Combined with XRD and Raman spectroscopy, the grain orientations within the samples were analyzed, and the presence of stress was verified. EBSD was employed to statistically examine the grain structure and size across samples. For samples with similar doping levels, grain size is the most influential factor in determining electrical characteristics. Further EBSD measurements reveal the relationship between resistivity and grain size as log(ρ) = −1.93 + 8.67/d. These findings provide a foundation for the quantitative control and application of polycrystalline 3C-SiC. This work offers theoretical evidence for optimizing the performance tuning of 3C-SiC ceramics and enhancing their effectiveness in electronic applications.
Downscaling challenges in IGZO transistors: A study on threshold voltage roll-up and roll-off effects
Jiye Li, Mengran Liu, Zhendong Jiang, Yuqing Zhang, Hua Xu, Lei Wang, Congwei Liao, Shengdong Zhang, Lei Lu
, Available online  
doi: 10.1088/1674-4926/24120005

Besides the common short-channel effect (SCE) of threshold voltage (Vth) roll-off during the channel length (L) downscaling of InGaZnO (IGZO) thin-film transistors (TFTs), an opposite Vth roll-up was reported in this work. Both roll-off and roll-up effects of Vth were comparatively investigated on IGZO transistors with varied gate insulator (GI), source/drain (S/D), and device architecture. For IGZO transistors with thinner GI, the SCE was attenuated due to the enhanced gate controllability over the variation of channel carrier concentration, while the Vth roll-up became more noteworthy. The latter was found to depend on the relative ratio of S/D series resistance (RSD) over channel resistance (RCH), as verified on transistors with different S/D. Thus, an ideal S/D engineering with small RSD but weak dopant diffusion is highly expected during the downscaling of L and GI in IGZO transistors.

Besides the common short-channel effect (SCE) of threshold voltage (Vth) roll-off during the channel length (L) downscaling of InGaZnO (IGZO) thin-film transistors (TFTs), an opposite Vth roll-up was reported in this work. Both roll-off and roll-up effects of Vth were comparatively investigated on IGZO transistors with varied gate insulator (GI), source/drain (S/D), and device architecture. For IGZO transistors with thinner GI, the SCE was attenuated due to the enhanced gate controllability over the variation of channel carrier concentration, while the Vth roll-up became more noteworthy. The latter was found to depend on the relative ratio of S/D series resistance (RSD) over channel resistance (RCH), as verified on transistors with different S/D. Thus, an ideal S/D engineering with small RSD but weak dopant diffusion is highly expected during the downscaling of L and GI in IGZO transistors.
Broadband photoluminescence and nonlinear chiroptical properties in chiral 2D halide perovskites
Dezhong Hu, Zhen Zhang, Kaixuan Zhang, Qian He, Weijie Zhao
, Available online  
doi: 10.1088/1674-4926/24110034

Two-dimensional (2D) chiral halide perovskites (CHPs) have attracted broad interest due to their distinct spin-dependent properties and promising applications in chiroptics and spintronics. Here, we report a new type of 2D CHP single crystals, namely R/S-3BrMBA2PbBr4. The chirality of the as-prepared samples is confirmed by exploiting circular dichroism spectroscopy, indicating a successful chirality transfer from chiral organic cations to their inorganic perovskite sublattices. Furthermore, we observed bright photoluminescence spanning from 380 to 750 nm in R/S-3BrMBA2PbBr4 crystals at room temperature. Such broad photoluminescence originates from free excitons and self-trapped excitons. In addition, efficient second-harmonic generation (SHG) performance was observed in chiral perovskite single crystals with high circular polarization ratios and non-linear optical circular dichroism. This demonstrates that R/S-3BrMBA2PbBr4 crystals can be used to detect and generate left- and right-handed circularly polarized light. Our study provides a new platform to develop high-performance chiroptical and spintronic devices.

Two-dimensional (2D) chiral halide perovskites (CHPs) have attracted broad interest due to their distinct spin-dependent properties and promising applications in chiroptics and spintronics. Here, we report a new type of 2D CHP single crystals, namely R/S-3BrMBA2PbBr4. The chirality of the as-prepared samples is confirmed by exploiting circular dichroism spectroscopy, indicating a successful chirality transfer from chiral organic cations to their inorganic perovskite sublattices. Furthermore, we observed bright photoluminescence spanning from 380 to 750 nm in R/S-3BrMBA2PbBr4 crystals at room temperature. Such broad photoluminescence originates from free excitons and self-trapped excitons. In addition, efficient second-harmonic generation (SHG) performance was observed in chiral perovskite single crystals with high circular polarization ratios and non-linear optical circular dichroism. This demonstrates that R/S-3BrMBA2PbBr4 crystals can be used to detect and generate left- and right-handed circularly polarized light. Our study provides a new platform to develop high-performance chiroptical and spintronic devices.
Reconfigurable devices based on two-dimensional materials for logic and analog applications
Liutianyi Zhang, Ping-Heng Tan, Jiangbin Wu
, Available online  
doi: 10.1088/1674-4926/24100005

In recent years, as the dimensions of the conventional semiconductor technology is approaching the physical limits, while the multifunction circuits are restricted by the relatively fixed characteristics of the traditional metal−oxide−semiconductor field-effect transistors, reconfigurable devices that can realize reconfigurable characteristics and multiple functions at device level have been seen as a promising method to improve integration density and reduce power consumption. Owing to the ultrathin structure, effective control of the electronic characteristics and ability to modulate structural defects, two-dimensional (2D) materials have been widely used to fabricate reconfigurable devices. In this review, we summarize the working principles and related logic applications of reconfigurable devices based on 2D materials, including generating tunable anti-ambipolar responses and demonstrating nonvolatile operations. Furthermore, we discuss the analog signal processing applications of anti-ambipolar transistors and the artificial intelligence hardware implementations based on reconfigurable transistors and memristors, respectively, therefore highlighting the outstanding advantages of reconfigurable devices in footprint, energy consumption and performance. Finally, we discuss the challenges of the 2D materials-based reconfigurable devices.

In recent years, as the dimensions of the conventional semiconductor technology is approaching the physical limits, while the multifunction circuits are restricted by the relatively fixed characteristics of the traditional metal−oxide−semiconductor field-effect transistors, reconfigurable devices that can realize reconfigurable characteristics and multiple functions at device level have been seen as a promising method to improve integration density and reduce power consumption. Owing to the ultrathin structure, effective control of the electronic characteristics and ability to modulate structural defects, two-dimensional (2D) materials have been widely used to fabricate reconfigurable devices. In this review, we summarize the working principles and related logic applications of reconfigurable devices based on 2D materials, including generating tunable anti-ambipolar responses and demonstrating nonvolatile operations. Furthermore, we discuss the analog signal processing applications of anti-ambipolar transistors and the artificial intelligence hardware implementations based on reconfigurable transistors and memristors, respectively, therefore highlighting the outstanding advantages of reconfigurable devices in footprint, energy consumption and performance. Finally, we discuss the challenges of the 2D materials-based reconfigurable devices.