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.
+ show detail
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 high reliability NOR flash cell in 50 nm node technology
Kevin Fang, Wei Wang, Yibai Xue, Fan Wang, Dong Pan, Yi Li, Jerry Zhou
, Available online  
doi: 10.1088/1674-4926/25030030

Along with NOR flash cell scaling down, dielectric burnout has gradually become one of the most important factors which affects product reliability, especially for high dropout voltage films. In this study, we demonstrate a reliability-enhanced NOR flash cell in 50 nm node technology through structural optimization of floating gate (FG) dimensions and active area profile. By synergistically increasing FG thickness, reducing FG width, and tuning cell-open depth, the control gate-to-active area corner distance expands by 22%, suppressing peak electric fields by 29% vertically and 18% horizontally. This structural innovation achieves: (1) 100× reduction in early-cycle burnout failures, (2) 7.38× time dependent dielectric breakdown lifetime improvement, while maintaining data retention and accelerating programming/erasing speeds by 15.4%/7.3%. The enhanced reliability enables 97.5% reduction in Fowler−Nordheim stress time during characterization program testing, providing a cost-effective solution for automotive-grade flash memories.

Along with NOR flash cell scaling down, dielectric burnout has gradually become one of the most important factors which affects product reliability, especially for high dropout voltage films. In this study, we demonstrate a reliability-enhanced NOR flash cell in 50 nm node technology through structural optimization of floating gate (FG) dimensions and active area profile. By synergistically increasing FG thickness, reducing FG width, and tuning cell-open depth, the control gate-to-active area corner distance expands by 22%, suppressing peak electric fields by 29% vertically and 18% horizontally. This structural innovation achieves: (1) 100× reduction in early-cycle burnout failures, (2) 7.38× time dependent dielectric breakdown lifetime improvement, while maintaining data retention and accelerating programming/erasing speeds by 15.4%/7.3%. The enhanced reliability enables 97.5% reduction in Fowler−Nordheim stress time during characterization program testing, providing a cost-effective solution for automotive-grade flash memories.
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.
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.
Breathable and skin-conformal electronic skin with dual-modality synchronous perception of pressure and temperature
Hao Zhu, Zhelin Jin, Tie Li, Guanggui Cheng, Jianning Ding
, Available online  
doi: 10.1088/1674-4926/25020031

The random nanofiber distribution in traditional electrospun membranes restricts the pressure sensing sensitivity and measurement range of electronic skin. Moreover, current multimodal sensing suffers from issues like overlapping signal outputs and slow response. Herein, a novel electrospinning method is proposed to prepare double-coupled microstructured nanofibrous membranes. Through the effect of high voltage electrostatic field in the electrospinning, the positively charged nanofibers are preferentially attached to the negatively charged foam surface, forming the ordered two-dimensional honeycomb porous nanofibrous membrane with three-dimensional spinous microstructure. Compared with the conventional random porous nanofibrous membrane, the bionic two-dimensional honeycomb and three-dimensional spinous dual-coupled microstructures in the ordered porous nanofibrous membrane endows the electronic skin with significantly improved mechanical properties (maximum tensile strain increased by 77% and fatigue resistance increased by 35%), air permeability (water vapor transmission rate increased by 16%) and sensing properties (pressure sensitivity increased by 276% and detection range increased by 137%). Furthermore, the electronic skin was constructed by means of a conformal composite ionic liquid functionalized nanofibrous membrane, and the real-time and interference-free dual-signal monitoring of pressure and temperature (maximum temperature coefficient of resistance: −0.918 °C−1) was realized.

The random nanofiber distribution in traditional electrospun membranes restricts the pressure sensing sensitivity and measurement range of electronic skin. Moreover, current multimodal sensing suffers from issues like overlapping signal outputs and slow response. Herein, a novel electrospinning method is proposed to prepare double-coupled microstructured nanofibrous membranes. Through the effect of high voltage electrostatic field in the electrospinning, the positively charged nanofibers are preferentially attached to the negatively charged foam surface, forming the ordered two-dimensional honeycomb porous nanofibrous membrane with three-dimensional spinous microstructure. Compared with the conventional random porous nanofibrous membrane, the bionic two-dimensional honeycomb and three-dimensional spinous dual-coupled microstructures in the ordered porous nanofibrous membrane endows the electronic skin with significantly improved mechanical properties (maximum tensile strain increased by 77% and fatigue resistance increased by 35%), air permeability (water vapor transmission rate increased by 16%) and sensing properties (pressure sensitivity increased by 276% and detection range increased by 137%). Furthermore, the electronic skin was constructed by means of a conformal composite ionic liquid functionalized nanofibrous membrane, and the real-time and interference-free dual-signal monitoring of pressure and temperature (maximum temperature coefficient of resistance: −0.918 °C−1) was realized.
Effect of nitrogen incorporation and surface passivation on photoluminescence properties of InAs-based nanowires
Ratmir Ustimenko, Danila Karaulov, Maxim Vinnichenko, Ilya Norvatov, Andrey Kaveev, Vladimir Fedorov, Ivan Mukhin, Dmitry Firsov
, Available online  
doi: 10.1088/1674-4926/25030041

InAsN nanowires on InAs stems were obtained using plasma-assisted molecular beam epitaxy on a SiOx/Si (111) substrate. Also, heterostructured InAs/InAsN and InAsN/InP nanowires were grown in the core/shell geometry. In the low-temperature photoluminescence spectra of the grown structures, spectral features are observed that correspond to the polytypic structure of nanowires with a predominance of the wurtzite phase and parasitic islands of the sphalerite phase. It was shown that the interband photoluminescence spectral features of InAsN nanowires experience a red shift relative to the pristine InAs nanowires. The incorporation of nitrogen reduces the bandgap by splitting the conduction band into two subbands. The position of the spectral features in the photoluminescence spectra confirms the formation of a nitride solid solution with a polytypic hexagonal structure, having a concentration of nitrogen atoms of up to 0.7%. Additional passivation of the nanowire surface with InP leads to a decrease in the intensity of nonradiative recombination and an improvement in the photoluminescent response of the nanowires, which makes it possible to detect photoluminescence emission at room temperature. Thus, by changing the composition and morphology of nanowires, it is possible to control their electronic structure, which allows varying the operating range of detectors and mid-IR radiation sources based on them.

InAsN nanowires on InAs stems were obtained using plasma-assisted molecular beam epitaxy on a SiOx/Si (111) substrate. Also, heterostructured InAs/InAsN and InAsN/InP nanowires were grown in the core/shell geometry. In the low-temperature photoluminescence spectra of the grown structures, spectral features are observed that correspond to the polytypic structure of nanowires with a predominance of the wurtzite phase and parasitic islands of the sphalerite phase. It was shown that the interband photoluminescence spectral features of InAsN nanowires experience a red shift relative to the pristine InAs nanowires. The incorporation of nitrogen reduces the bandgap by splitting the conduction band into two subbands. The position of the spectral features in the photoluminescence spectra confirms the formation of a nitride solid solution with a polytypic hexagonal structure, having a concentration of nitrogen atoms of up to 0.7%. Additional passivation of the nanowire surface with InP leads to a decrease in the intensity of nonradiative recombination and an improvement in the photoluminescent response of the nanowires, which makes it possible to detect photoluminescence emission at room temperature. Thus, by changing the composition and morphology of nanowires, it is possible to control their electronic structure, which allows varying the operating range of detectors and mid-IR radiation sources based on them.
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 1.25 GHz, 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 1.25 GHz, 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.
Simulation and fabrication of vertical channel transistors with self-aligned high-κ metal gates using ion implantation for source/drain doping
Penghui Sun, Yongkui Zhang, Jun Luo
, Available online  
doi: 10.1088/1674-4926/25030043

In vertical channel transistors (VCTs), source/drain ion implantation (I/I) represents a significant technical challenge due to inherent three-dimensional structural constraints, which induce complications such as difficulties in dummy gate formation and shadowing effects of I/I. This article systematically investigates the impact of different implantation conditions on the performance of VCTs with and without dummy gates through TCAD simulation. It reveals the significant role of the lightly doped regions (LDRs) naturally formed due to ion implantation in source/drain of VCTs. Furthermore, it was found that VCT without dummy gates can achieve an approximately 27% increase in on-state current (Ion) under the same implantation conditions, and can greatly simplify the process flow and reduce costs. Finally, N-type and P-type VCTs were successfully fabricated using this implantation method.

In vertical channel transistors (VCTs), source/drain ion implantation (I/I) represents a significant technical challenge due to inherent three-dimensional structural constraints, which induce complications such as difficulties in dummy gate formation and shadowing effects of I/I. This article systematically investigates the impact of different implantation conditions on the performance of VCTs with and without dummy gates through TCAD simulation. It reveals the significant role of the lightly doped regions (LDRs) naturally formed due to ion implantation in source/drain of VCTs. Furthermore, it was found that VCT without dummy gates can achieve an approximately 27% increase in on-state current (Ion) under the same implantation conditions, and can greatly simplify the process flow and reduce costs. Finally, N-type and P-type VCTs were successfully fabricated using this implantation method.
Eco-sustainable biosynthesis of CoFe2O4 nanoparticles using apple extract for multifunctional applications
Heba Hussein, Sobhy Sayed Ibrahim, Sherif Ahmed Khairy
, Available online  
doi: 10.1088/1674-4926/25040013

This study investigates the effect of apple extract on CoFe2O4 nanoparticles synthesized via a green self-ignition method. High resolution transmission electron microscope (HRTEM) showed nanometric particles with varied shapes, while X-ray diffraction (XRD) and Rietveld refinement confirmed a facecentered cubic (Fd3̅m) structure. Mössbauer spectroscopy revealed a Zeeman sextet pattern with only Fe3+ ions. Ultra violet vissible nearinfrared (UV–Vis–NIR) spectra indicated strong absorbance in the visible and NIR regions, suggesting optoelectronic potential. The nanoparticles demonstrated high photo-Fenton catalytic efficiency, degrading 96.88% of Methylene Blue under visible light. They also exhibited 100% adsorption capacities for Cr3+ and Pb2+, making them effective for water treatment. These properties were attributed to a large surface area (347.04 m2/g), mesoporous structure, and mixed spinel phase. ANOVA and Tukey’s honestly significant difference (HSD) tests confirmed that contact time and adsorbent dosage significantly affected pollutant removal. Additionally, strong antimicrobial activity highlighted their biotechnological relevance. The inclusion of apple extract enhanced structural and functional features, expanding application prospects in spin valves, magnetic recording, refrigeration, microwave technologies (C to Ku bands), optoelectronics, and biotechnology. Future work should explore the photo-Fenton degradation mechanism and optimize synthesis for scalable production, aiming to maximize their industrial utility.

This study investigates the effect of apple extract on CoFe2O4 nanoparticles synthesized via a green self-ignition method. High resolution transmission electron microscope (HRTEM) showed nanometric particles with varied shapes, while X-ray diffraction (XRD) and Rietveld refinement confirmed a facecentered cubic (Fd3̅m) structure. Mössbauer spectroscopy revealed a Zeeman sextet pattern with only Fe3+ ions. Ultra violet vissible nearinfrared (UV–Vis–NIR) spectra indicated strong absorbance in the visible and NIR regions, suggesting optoelectronic potential. The nanoparticles demonstrated high photo-Fenton catalytic efficiency, degrading 96.88% of Methylene Blue under visible light. They also exhibited 100% adsorption capacities for Cr3+ and Pb2+, making them effective for water treatment. These properties were attributed to a large surface area (347.04 m2/g), mesoporous structure, and mixed spinel phase. ANOVA and Tukey’s honestly significant difference (HSD) tests confirmed that contact time and adsorbent dosage significantly affected pollutant removal. Additionally, strong antimicrobial activity highlighted their biotechnological relevance. The inclusion of apple extract enhanced structural and functional features, expanding application prospects in spin valves, magnetic recording, refrigeration, microwave technologies (C to Ku bands), optoelectronics, and biotechnology. Future work should explore the photo-Fenton degradation mechanism and optimize synthesis for scalable production, aiming to maximize their industrial utility.
A minireview on technology and application of silicon integrated single crystal perovskite
Jing Weng, Molang Cai, Xu Pan, Xing Li
, Available online  
doi: 10.1088/1674-4926/25040012

Metal halide perovskites (MHPs) have become promising optoelectronic materials due to their long carrier lifetimes and high mobility. However, the presence of defects and ion migration in MHPs results in high and unstable dark currents, which compromise the stability and detection performance of MHP-based optoelectronic devices. Interfacial engineering has proven to be an effective strategy to reduce defect density in MHPs and suppress ion migration. Given the compatibility of silicon (Si) and MHP processing technologies, coupled with the simplicity and cost-effectiveness of the approach, the integration of MHPs onto Si surfaces has become a prominent area of research. This integration not only enhances device performance but also expands their practical applications. This review provides an overview of the integration technologies for Si and single crystal MHPs, evaluates the advantages and limitations of various integration schemes (including inverse temperature crystallization, vacuum-assisted vapor deposition, and anti-solvent vapor-assisted crystallization), and explores the practical applications of Si/MHP-integrated optoelectronic devices with different structures. These optimized devices exhibit outstanding performance in X-ray detection, multi-wavelength photodetection, and circularly polarized light detection. This review provides a systematic reference for technological innovation and application expansion of Si/MHP-integrated devices.

Metal halide perovskites (MHPs) have become promising optoelectronic materials due to their long carrier lifetimes and high mobility. However, the presence of defects and ion migration in MHPs results in high and unstable dark currents, which compromise the stability and detection performance of MHP-based optoelectronic devices. Interfacial engineering has proven to be an effective strategy to reduce defect density in MHPs and suppress ion migration. Given the compatibility of silicon (Si) and MHP processing technologies, coupled with the simplicity and cost-effectiveness of the approach, the integration of MHPs onto Si surfaces has become a prominent area of research. This integration not only enhances device performance but also expands their practical applications. This review provides an overview of the integration technologies for Si and single crystal MHPs, evaluates the advantages and limitations of various integration schemes (including inverse temperature crystallization, vacuum-assisted vapor deposition, and anti-solvent vapor-assisted crystallization), and explores the practical applications of Si/MHP-integrated optoelectronic devices with different structures. These optimized devices exhibit outstanding performance in X-ray detection, multi-wavelength photodetection, and circularly polarized light detection. This review provides a systematic reference for technological innovation and application expansion of Si/MHP-integrated devices.
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.
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.
Mid-wavelength infrared planar junction photodetector based on InAs/GaSb Type-Ⅱ superlattices
Shihao Zhang, Hongyue Hao, Ye Zhang, Shuo Wang, Xiangyu Zhang, Ruoyu Xie, Lingze Yao, Faran Chang, Yifan shan, Haofeng Liu, Guowei Wang, Donghai Wu, Dongwei Jiang, Yingqiang Xu, Zhichuan Niu, Wenjing Dong
, Available online  
doi: 10.1088/1674-4926/24120014

In this paper, a planar junction mid-wavelength infrared (MWIR) photodetector based on an InAs/GaSb type-Ⅱ superlattices (T2SLs) is reported. The Intrinsic-πMN superlattices was grown by the molecular beam epitaxy (MBE), followed with a ZnS layer grown by the chemical vapor deposition (CVD). The p-type contact layer was constructed by thermal diffusion in the undoped superlattices. The Zinc atom was successfully realised in to the superlattice and a PπMN T2SL structure was constructed. Furthermore, the effects of different diffusion temperatures on the dark current performance of the devices were researched. The 50% cut-off wavelength of the photodetector is 5.26 μm at 77 K with 0 V bias. The minimum dark current density is 8.67 × 10−5 A/cm2 and the maximum quantum efficiency of 42.5%, and the maximum detectivity reaches 3.90 × 1010 cm·Hz1/2/W at 77 K. The 640 × 512 focal plane arrays (FPA) based on the planner junction were fabricated afterwards. The FPA achieves a noise equivalent temperature difference (NETD) of 539 mK.

In this paper, a planar junction mid-wavelength infrared (MWIR) photodetector based on an InAs/GaSb type-Ⅱ superlattices (T2SLs) is reported. The Intrinsic-πMN superlattices was grown by the molecular beam epitaxy (MBE), followed with a ZnS layer grown by the chemical vapor deposition (CVD). The p-type contact layer was constructed by thermal diffusion in the undoped superlattices. The Zinc atom was successfully realised in to the superlattice and a PπMN T2SL structure was constructed. Furthermore, the effects of different diffusion temperatures on the dark current performance of the devices were researched. The 50% cut-off wavelength of the photodetector is 5.26 μm at 77 K with 0 V bias. The minimum dark current density is 8.67 × 10−5 A/cm2 and the maximum quantum efficiency of 42.5%, and the maximum detectivity reaches 3.90 × 1010 cm·Hz1/2/W at 77 K. The 640 × 512 focal plane arrays (FPA) based on the planner junction were fabricated afterwards. The FPA achieves a noise equivalent temperature difference (NETD) of 539 mK.
Fabrication, TCAD and compact model verification of TIPS-pentacene organic thin film transistor
Shubham Dadhich, Vivek Upadhyaya, Garima Mathur
, Available online  
doi: 10.1088/1674-4926/24090029

As organic thin film transistors (OTFTs) are set to play a crucial role in flexible and cost-effective electronic applications, this paper investigates a high-mobility 6,13-bis(triisopropylsilylethynyl) Pentacene (TIPS-Pentacene) OTFT for use in flexible electronics. The development of such high-mobility devices necessitates precise device modeling to support technology optimisation and circuit design. The details of numerical simulation technique is discussed, in which, the electrical behavior of the device is well captured by fine tuning basic semiconductor equations. This technology computer-aided design (TCAD) has been validated with eprimental data. In addition, we have discussed about compact model fitting of the devices as well as parameter extraction procedure employed. This includes verification of ATLAS FEM based results against experimental data gained from fabricated OTFT devices. Simulations for p-type TFT-based inverter are also performed to assess the performance of compact model in simple circuit simulation.

As organic thin film transistors (OTFTs) are set to play a crucial role in flexible and cost-effective electronic applications, this paper investigates a high-mobility 6,13-bis(triisopropylsilylethynyl) Pentacene (TIPS-Pentacene) OTFT for use in flexible electronics. The development of such high-mobility devices necessitates precise device modeling to support technology optimisation and circuit design. The details of numerical simulation technique is discussed, in which, the electrical behavior of the device is well captured by fine tuning basic semiconductor equations. This technology computer-aided design (TCAD) has been validated with eprimental data. In addition, we have discussed about compact model fitting of the devices as well as parameter extraction procedure employed. This includes verification of ATLAS FEM based results against experimental data gained from fabricated OTFT devices. Simulations for p-type TFT-based inverter are also performed to assess the performance of compact model in simple circuit simulation.
Mesa-structured AlGaAsSb APD: dark current and noise analysis
Yuhang He, Rui Wang, Yan Liang, Yingqiang Xu, Guowei Wang, Haiqiao Ni, Shuo Wang, Zhichuan Niu, Xiaohong Yang
, Available online  
doi: 10.1088/1674-4926/25020025

Avalanche photodiode (APD) is a kind of photodetector with important applications in optical communication, LIDAR and other fields. APDs fabricated using the recently developed AlGaAsSb as the multiplication material exhibit excellent noise performance. In this work, we report a low-noise separate absorption, grading, charge, and multiplication (SAGCM) InGaAs/AlGaAsSb APD operating at 1550 nm. A double-mesa structure was fabricated to reduce the dark current. Numerical simulations were conducted to compare two different mesa-structured APDs. By analyzing the electric field distribution, it was found that the electric field at the edge of the multiplication region in the double-mesa APD is nearly 100 kV/cm lower than that of the single-mesa structure. Experimental results demonstrate that after device punch-through, the double-mesa APD’s dark current can be reduced by up to four times compared to the single-mesa APD. Quantitative analysis of the dark current components in the AlGaAsSb APD further confirms that the low sidewall electric field in the double-mesa structure effectively suppresses the trap-assisted tunneling. Additionally, noise measurements indicate a k-value of approximately 0.014, which is significantly lower than that of traditional multiplication materials. This work provides preliminary validation for further performance improvements in low noise and low dark current AlGaAsSb APDs.

Avalanche photodiode (APD) is a kind of photodetector with important applications in optical communication, LIDAR and other fields. APDs fabricated using the recently developed AlGaAsSb as the multiplication material exhibit excellent noise performance. In this work, we report a low-noise separate absorption, grading, charge, and multiplication (SAGCM) InGaAs/AlGaAsSb APD operating at 1550 nm. A double-mesa structure was fabricated to reduce the dark current. Numerical simulations were conducted to compare two different mesa-structured APDs. By analyzing the electric field distribution, it was found that the electric field at the edge of the multiplication region in the double-mesa APD is nearly 100 kV/cm lower than that of the single-mesa structure. Experimental results demonstrate that after device punch-through, the double-mesa APD’s dark current can be reduced by up to four times compared to the single-mesa APD. Quantitative analysis of the dark current components in the AlGaAsSb APD further confirms that the low sidewall electric field in the double-mesa structure effectively suppresses the trap-assisted tunneling. Additionally, noise measurements indicate a k-value of approximately 0.014, which is significantly lower than that of traditional multiplication materials. This work provides preliminary validation for further performance improvements in low noise and low dark current AlGaAsSb APDs.
High-speed electro-absorption modulated laser
Zhenyao Li, Chen Lyu, Xuliang Zhou, Mengqi Wang, Haotian Qiu, Yejin Zhang, Hongyan Yu, Jiaoqing Pan
, Available online  
doi: 10.1088/1674-4926/25030015

Currently, the global 5G network, cloud computing, and data center industries are experiencing rapid development. The continuous growth of data center traffic has driven the vigorous progress in high-speed optical transceivers for optical interconnection within data centers. The electro-absorption modulated laser (EML), which is widely used in optical fiber communications, data centers, and high-speed data transmission systems, represents a high-performance photoelectric conversion device. Compared to traditional directly modulated lasers (DMLs), EMLs demonstrate lower frequency chirp and higher modulation bandwidth, enabling support for higher data rates and longer transmission distances. This article introduces the composition, working principles, manufacturing processes, and applications of EMLs. It reviews the progress on advanced indium phosphide (InP)-based EML devices from research institutions worldwide, while summarizing and comparing data transmission rates and key technical approaches across various studies.

Currently, the global 5G network, cloud computing, and data center industries are experiencing rapid development. The continuous growth of data center traffic has driven the vigorous progress in high-speed optical transceivers for optical interconnection within data centers. The electro-absorption modulated laser (EML), which is widely used in optical fiber communications, data centers, and high-speed data transmission systems, represents a high-performance photoelectric conversion device. Compared to traditional directly modulated lasers (DMLs), EMLs demonstrate lower frequency chirp and higher modulation bandwidth, enabling support for higher data rates and longer transmission distances. This article introduces the composition, working principles, manufacturing processes, and applications of EMLs. It reviews the progress on advanced indium phosphide (InP)-based EML devices from research institutions worldwide, while summarizing and comparing data transmission rates and key technical approaches across various studies.
Sintering and electrical characteristics of In2O3-based targets doped with multiple components for solar cells
Jianzhong Liao, Fangzhou Wu, Jiwen Xu, Guisheng Zhu, Fei Shang, Huarui Xu
, Available online  
doi: 10.1088/1674-4926/24090038

To address the escalating demand for high-mobility transparent and conductive oxide (TCO) films in heterojunction solar cells, multiple components doped In2O3 targets were proposed. The In2O3 targets incorporating 1 wt.% CeO2, Ta2O5 and TiO2 were sintered under different sintering temperatures and times. All the targets show the cubic bixbyite phase of In2O3. The microstructure illustrates densely packed fine grains and uniform elemental distribution. Notably, increasing the sintering temperature and holding time contributes to effective pore elimination within the targets. A relative density of greater than 99.5% is obtained for the targets sintered at 1500 °C for 4 and 6 h, and the corresponding optimum resistivity decreases from 1.068 × 10³ Ω·cm to 9.73 × 10−4 Ω·cm. These results provide the experimental basis of fabricating In2O3-based targets for depositing high mobility TCO films by magnetron sputtering.

To address the escalating demand for high-mobility transparent and conductive oxide (TCO) films in heterojunction solar cells, multiple components doped In2O3 targets were proposed. The In2O3 targets incorporating 1 wt.% CeO2, Ta2O5 and TiO2 were sintered under different sintering temperatures and times. All the targets show the cubic bixbyite phase of In2O3. The microstructure illustrates densely packed fine grains and uniform elemental distribution. Notably, increasing the sintering temperature and holding time contributes to effective pore elimination within the targets. A relative density of greater than 99.5% is obtained for the targets sintered at 1500 °C for 4 and 6 h, and the corresponding optimum resistivity decreases from 1.068 × 10³ Ω·cm to 9.73 × 10−4 Ω·cm. These results provide the experimental basis of fabricating In2O3-based targets for depositing high mobility TCO films by magnetron sputtering.
Research on optical soliton characteristics GaSb-based ~2 μm wavelength two-section integrated optical chip
Wenjun Yu, Zhongliang Qiao, Xiang Li, Jia Xu Brian Sia, Dengqun Weng, Xiaohu Hou, Zaijin Li, Lin Li, Hao Chen, Zhibin Zhao, Yi Qu, Chongyang Liu, Hong Wang, Yu Zhang, Zhichuan Niu
, Available online  
doi: 10.1088/1674-4926/25030011

The optical soliton characteristics of GaSb-based ~2 μm wavelength integrated optical chips have broad application prospects in optoelectronic fields such as optical communications, infrared countermeasures, and gas environment monitoring. In the research of two-section integrated optical chips, more attention is paid to their passive mode-locked characteristics. The ability of its structure to generate stable soliton transmission has not yet been studied, which will limit its further application in high-performance near-mid infrared optoelectronic technology. In this paper, we design and prepare a GaSb-based ~2 μm wavelength two-section integrated semiconductor laser chip structure, and test and analyze its related properties of soliton, including power−injection current−voltage (PIV), temperature and mode-locked characteristics. Experimental results show that the chip can achieve stable mode-locked operation at nearly ~2 μm wavelength and present the working characteristics of near optical soliton states and multi-peak optical soliton states. By comparing and analyzing the measured optical pulse sequence curve with the numerical fitting based on the pure fourth order soliton approximation solution, it is confirmed that the two-section integrated optical chip structure can generate stable transmission of multi-peak optical soliton. This provides a research direction for developing near-mid infrared mode-locked integrated optical chips with high-performance property of optical soliton.

The optical soliton characteristics of GaSb-based ~2 μm wavelength integrated optical chips have broad application prospects in optoelectronic fields such as optical communications, infrared countermeasures, and gas environment monitoring. In the research of two-section integrated optical chips, more attention is paid to their passive mode-locked characteristics. The ability of its structure to generate stable soliton transmission has not yet been studied, which will limit its further application in high-performance near-mid infrared optoelectronic technology. In this paper, we design and prepare a GaSb-based ~2 μm wavelength two-section integrated semiconductor laser chip structure, and test and analyze its related properties of soliton, including power−injection current−voltage (PIV), temperature and mode-locked characteristics. Experimental results show that the chip can achieve stable mode-locked operation at nearly ~2 μm wavelength and present the working characteristics of near optical soliton states and multi-peak optical soliton states. By comparing and analyzing the measured optical pulse sequence curve with the numerical fitting based on the pure fourth order soliton approximation solution, it is confirmed that the two-section integrated optical chip structure can generate stable transmission of multi-peak optical soliton. This provides a research direction for developing near-mid infrared mode-locked integrated optical chips with high-performance property of optical soliton.
Study of a novel SiC-based light initiated multi-gate semiconductor switch
Chongbiao Luan, Jianqiang Yuan, Hongwei Liu, Longfei Xiao, Huiru Sha, Le Xu, Yang He, Lingyun Wang, Hongtao Li, Yupeng Huang
, Available online  
doi: 10.1088/1674-4926/25020033

To optimize turn on velocity of the SiC LIMS, we proposed a new structure for the LIMS that incorporates an optimized n+ layer and a multi-light triggered electrode design for the anode. The chip size is 5.5 mm × 5.5 mm in dimension. The experiment results indicate that the saturation laser energy required to trigger the prepared SiC LIMS has been decreased from 1.8 mJ to 40 μJ, with the forward blocking voltage of the prepared SiC LIMSs capable of withstanding over 7000 V. The leakage current is about 0.3 μA at room temperature, and the output current density achieves 4.25 kA/cm2 (with di/dt larger than 20 kA/μs).

To optimize turn on velocity of the SiC LIMS, we proposed a new structure for the LIMS that incorporates an optimized n+ layer and a multi-light triggered electrode design for the anode. The chip size is 5.5 mm × 5.5 mm in dimension. The experiment results indicate that the saturation laser energy required to trigger the prepared SiC LIMS has been decreased from 1.8 mJ to 40 μJ, with the forward blocking voltage of the prepared SiC LIMSs capable of withstanding over 7000 V. The leakage current is about 0.3 μA at room temperature, and the output current density achieves 4.25 kA/cm2 (with di/dt larger than 20 kA/μs).
Machine learning facilitates the development of interconnecting layers for perovskite/silicon heterojunction tandem solar cells with proof-of-concept efficiency > 38%
Xuejiao Wang, Guanlan Chen, Ying Liu, Guangyi Wang, Wei Han, Jin Wang, Pengfei Liu, Jilei Wang, Shaojuan Bao, Bo Yu, Xinliang Chen, Shengzhi Xu, Ying Zhao, Xiaodan Zhang
, Available online  
doi: 10.1088/1674-4926/25050011

As the development of single-junction solar cells reaches a bottleneck, tandem solar cells have emerged as a critical pathway to further enhance power conversion efficiency. Among them, monolithic perovskite/silicon heterojunction tandem solar cells are currently the fastest-growing technology, achieving the highest efficiencies at relatively low costs. The interconnecting layer, which connects the two sub-cells, plays a crucial role in tandem cell performance. It collects electrons and holes from the respective sub-cells and facilitates recombination and tunneling at the interface. Therefore, the properties of the interconnecting layer are pivotal to the overall device performance. In this work, we applied statistical analysis and machine learning algorithms to systematically analyze the interconnecting layer. A comprehensive dataset on interconnecting layer parameters was established, and predictive modeling was performed using Lasso linear regression, random forest, and multilayer perceptron (a type of neural network). The analysis revealed key feature importance for experimental parameters, providing valuable insights into the application of interconnecting layers in perovskite/silicon heterojunction tandem solar cells. The final optimized interconnecting layer can achieve a proof-of-concept efficiency of 38.17%, providing guidance and direction for the development of monolithic perovskite/silicon tandem solar cells.

As the development of single-junction solar cells reaches a bottleneck, tandem solar cells have emerged as a critical pathway to further enhance power conversion efficiency. Among them, monolithic perovskite/silicon heterojunction tandem solar cells are currently the fastest-growing technology, achieving the highest efficiencies at relatively low costs. The interconnecting layer, which connects the two sub-cells, plays a crucial role in tandem cell performance. It collects electrons and holes from the respective sub-cells and facilitates recombination and tunneling at the interface. Therefore, the properties of the interconnecting layer are pivotal to the overall device performance. In this work, we applied statistical analysis and machine learning algorithms to systematically analyze the interconnecting layer. A comprehensive dataset on interconnecting layer parameters was established, and predictive modeling was performed using Lasso linear regression, random forest, and multilayer perceptron (a type of neural network). The analysis revealed key feature importance for experimental parameters, providing valuable insights into the application of interconnecting layers in perovskite/silicon heterojunction tandem solar cells. The final optimized interconnecting layer can achieve a proof-of-concept efficiency of 38.17%, providing guidance and direction for the development of monolithic perovskite/silicon tandem solar cells.
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.
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.
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.
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.
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.
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.
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.
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.
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.