Inorganic cesium lead iodide (CsPbI₃) perovskites are promising photovoltaic materials owing to their excellent thermal stability and optoelectronic properties. However, CsPbI₃ film fabricated via solution processing typically suffers from high defect densities and detrimental residual tensile stress due to uncontrolled crystallization and thermal expansion mismatch with the substrate, which impedes its practical application. Herein, we introduce ammonium benzenesulfonate (ABS) as a bifunctional additive to modulate crystallization, thereby passivating defects and regulating residual stress. The sulfonate group of ABS coordinates with undercoordinated Pb²⁺ ions, while its ammonium group forms hydrogen bonds with iodide ions. The molecular structure of ABS bridges adjacent [PbI₆]⁴⁻ octahedra at grain boundaries. This dual interaction effectively enhanced crystallinity, suppressed non-radiative recombination, and improved structural stability. As a result, ABS-modified CsPbI₃-based perovskite solar cells achieve an impressive power conversion efficiency (PCE) of 21.21% under standard illumination. Remarkably, they deliver a PCE of 40.85% under indoor lighting conditions. Moreover, unencapsulated devices retains 91% of their initial PCE after 800 h of storage in ambient air at a relative humidity of 5%.

Thermoelectric power generation has attracted significant interest for its capability to directly convert thermal energy into electricity. Among various configurations, thin-film thermoelectric generators (TEGs) stand out due to their lightweight nature and facile integration, offering promising applications in waste heat recovery and wearable electronics. However, the performance of such devices under complex mechanical conditions, particularly under biaxial tensile strain, remains underexplored. In this work, we designed and fabricated a thin-film TEG insensitive to tensile strain and performed a parametric analysis using validated 3D numerical simulations to evaluate the effects of environmental conditions, material properties, and geometric parameters. Notably, the designed device maintained stable electrical performance under various biaxial tensile strains. Owing to its miniature and thin profile, variations in any component of the generator significantly affected its electrical performance. The results indicated that reduced thermal conductivity of the substrate and Ecoflex layer, as well as a thinner substrate, enhance the output voltage. Furthermore, longer thermoelectric legs within a certain range contributed to higher output voltage. Higher output voltage was more readily achieved when the inner radius length was close to the radius of the heat source. This work provides valuable insights for the development of high-performance compliant TEGs applicable in dynamic mechanical environments, such as complex stretching in the back and shoulder–elbow regions induced by human motion.

To address the demand for sub-100-nm overlay accuracy in wafer bonding for 3D integration, this study proposes an extended overlay assessment model integrating physical mechanisms and data-driven approaches, along with a correlation analysis methodology with process parameters. Rigid-body models inadequately characterize systematic deformations from crystalline anisotropy and process stresses. To overcome this, we construct an extended overlay model based on Zernike polynomials, incorporating physically meaningful terms for precise description of non-uniform wafer deformation. An innovative Zernike term selection strategy combining physics-guided pre-screening and AIC-optimized stepwise regression resolves overfitting/underfitting, enhancing generalizability and interpretability. Validation using Patterned Wafer Geometry (PWG) data shows the model achieves R² > 0.70 for both net bonding deformation and lithography-compensable components, demonstrating excellent deformation decomposition. Correlation analysis of multiple process experiments reveals strong correlations (|r| > 0.85) between key process parameters (e.g., peak bonding head force) and specific Zernike modes, providing evidence for suppressing detrimental deformations via process optimization. This research establishes a complete framework from theory to experimental verification and process traceability, laying a foundation for mechanism diagnosis, predictive compensation, and closed-loop control in high-precision wafer bonding.

To improve the breakdown voltage (BV)−specific on-resistance (R_on,sp) trade-off and enhance manufacturability, this article proposes a novel lateral diffused metal−oxide−semiconductor (LDMOS) structure that features a split gate and split contact field plate (CFP). This novel structure requires no additional bias voltages, masks, or process steps, making it fully compatible with the bipolar-CMOS-DMOS (BCD) process flow. The physical mechanisms are elucidated through Technology computer-aided design (TCAD) simulations. In the on-state, the positively biased split gate forms an accumulation layer at the drift region surface, thereby reducing R_on,sp. In the off-state, both the split gate and split CFP introduce additional electric-field peaks that smooth the lateral electric field, thus preserving a high BV. Compared with the conventional CFP-LDMOS, the proposed CFP-LDMOS achieves an 8.52% reduction in R_on,sp without compromising BV, leading to an 8.07% improvement in the figure of merit (FOM). Notably, the proposed structure can be extended to LDMOS devices across different voltage levels within BCD platforms, demonstrating its broad applicability.

Integrating electrochromic (EC) and photochromic (PC) functions within a single material system holds great significance for the development of next-generation intelligent responsive materials. Traditional organic photochromic materials are all small molecules and oligomers, which require the photochemical response of specific photosensitive groups. However, PEDOT:PSS, a classic electrochromic polymer, has never been reported to exhibit photochromic properties due to the absence of photosensitive groups. Herein, we report for the first time the photochromic properties of PEDOT:PSS films, demonstrating their simultaneous capability of multi-field coupling response in the aspects of light, electricity and chemistry. The composite film undergoes a rapid color change from light blue to dark blue under ultraviolet light irradiation. This is attributed to the transformation process from the bipolarons state to the polarons state in the PEDOT:PSS, induced by photogenerated electrons as confirmed by EPR and Raman analyses. Furthermore, the developed hydrogel system enhances charge separation, yielding a 30.1% relative transmittance change and month-long stability. This work fills the long-standing gap in the understanding of the photochromic and electrochromic mechanisms of PEDOT:PSS, providing fundamental insights into carrier dynamics at organic-inorganic interfaces and laying the foundation for the development of multi-mode stimuli-responsive devices.

In recent years, position-sensitive detectors (PSDs) have found widespread application in displacement measurement, optical measurement, imaging, and laser communication, owing to their high spatial resolution and rapid response capabilities. However, the performance and operating mechanisms of perovskite-based PSDs remain insufficiently elucidated. In this work, we fabricated a high-sensitivity self-powered PSD based on a ZnO/P(VDF-TrFE)−CH₃NH₃PbI₃(MAPbI₃) heterojunction. Systematic optimization revealed an optimal P(VDF-TrFE) doping concentration of 5 mg/mL, enabling the device to achieve a remarkable positional sensitivity (PS) of 307.03 mV/mm with a minimum nonlinearity of 1.02%. Furthermore, the intrinsic pyroelectric property of P(VDF-TrFE) induces a significant pyroelectrically enhanced lateral photovoltaic effect (LPE), boosting the PS to 511.33 mV/mm—an enhancement of 166.5%. The heterojunction PSD maintains effective operational performance over an electrode spacing range of 0.5−2.2 mm. While the LPE response declines with increasing spacing, a considerable pyroelectric effect (PE)-enhanced PS of 70.67 mV/mm is retained even at 2.2 mm. Importantly, we demonstrate multi-wavelength imaging by exploiting both the inherent LPE response and its pyroelectrically enhanced counterpart, with imaging intensity tunable via electrode spacing control. This study provides crucial insights into the LPE behavior of the heterojunction and systematically clarifies the mechanism by which the PE modulates device performance and imaging capabilities.

Sb₂S₃ has attracted increasing attention for next-generation photovoltaics due to its excellent materials and optoelectronic properties, especially a suitable bandgap (~1.75 eV) for indoor photovoltaics and silicon-based tandem solar cells. However, the highest power conversion efficiency (PCE) report thus far for Sb₂S₃ solar cells is 8.26%, lagging far behind its theoretical efficiency limit (~28%). This study aims to scrutinize the important roles of hole transport layers (HTLs) in near-intrinsic Sb₂S₃ solar cells. It is found that the device efficiencies of both of p-type Sb₂S₃ and n-type Sb₂S₃ based planar solar cells are significantly enhanced with the incorporation of Spiro-OMeTAD HTL, further confirmed by the SCAPS simulation. The specific roles of HTL on promoting the interface hole extraction in Sb₂S₃ solar cells are elucidated. Then the performance optimization is conducted by systematically optimizing key parameters of Sb₂S₃ absorbers, such as absorber thickness, defect density, and doping concentration. Furthermore, several typical inorganic HTL candidates for replacing Spiro-OMeTAD were explored for Sb₂S₃ solar cells, revealing that the Cu₂O HTL based device exhibits a highest PCE of 23.09%. This work highlights the necessity of HTLs for devices based on near-intrinsic Sb₂S₃ and provides valuable insights for further enhancing the performance of Sb₂S₃ solar cells.

To study MEMS power detection chips more accurately, a thermo-electromechanical coupling model is proposed in this work. The fringing capacitance is included in the model, further refining the expression for the parallel-plate capacitance. Moreover, the squeeze-film damping and thermoelastic damping are considered in the second-order differential equation to study the cantilever vibration. It is found that the squeeze-film damping is the dominant damping of the system, and the cantilever beam exhibits linear expansion with increasing temperature. A dual-channel microwave detection chip is fabricated and measured, and the return loss reaches its minimum of −66.46 dB at 9 GHz, indicating optimal impedance matching at the central frequency. Moreover, the measured sensitivity is approximately 65.6 fF/W. Critically, the measured resonant frequency of the cantilever beam is 115.7 kHz, which is orders of magnitude lower than the input signal frequency. This large separation ensures that the sensor operates in a stable, non-resonant regime, thereby guaranteeing linearity and reliability. These findings demonstrate the excellent microwave performance of the power sensor fabricated in this work, providing valuable insights for optimizing the design of MEMS microwave power detection chips.

Charged quantum dots (QD) coupled to micropillar cavities are key platforms for studying photon-spin interactions. However, most research involves quantum dots charged via external excitation, resulting in short charge lifetimes. We demonstrate a device where a quantum dot confines an extra electron through δ-doping and couples to a high Q-factor (about 11 000) micropillar cavity mode (CM). We propose a precise calibration process for the micropillar cavity to achieve coupling between the negatively charged exciton (X−) transitions and CM at low temperatures. Micro-photoluminescence (μPL) spectroscopy confirms X− transitions and their coupling with CM at 7 K, with the coupled emission intensity enhanced about tenfold relative to the uncoupled state. The X− transitions and CM both show low spectral fluctuations at the change of polarization of incident light (X− 2.66 μeV, CM 3 μeV).

The computational cost of TCAD simulations is becoming prohibitively high with the complexity of advanced process technologies, making simulation acceleration a critical research priority. While end-to-end surrogate models mapping process recipes to device structures and characteristics offer a promising alternative, their application is often limited by poor generalizability and explainability. In this work, we present MPNet, a modular deep learning surrogate modeling framework for process TCAD. MPNet comprises distinct surrogate models for individual process modules, which are assembled into an integrated framework. These modular models employ a novel UNet-attention feature evolution method to capture the complex evolutions of device geometry and doping profiles. Each module can be trained separately on its individual process, after which the modules are cascaded and jointly fine-tuned to minimize error accumulation throughout the cascade. The efficacy of the proposed MPNet framework is demonstrated through a MOSFET integrated process TCAD case study. Results show that MPNet achieves a computational speedup of over 103 times compared to conventional TCAD, while maintaining predictive fidelity exceeding 98%. Finally, to illustrated the application of the proposed framework, MPNet is coupled with a PSO algorithm, showcasing its utility for fast process optimization to meet specific process targets.

Two-dimensional (2D) magnetic materials have attracted significant attention owing to their tunable magnetic properties and prospective applications in next-generation spintronic devices. However, their practical utilization is often limited by poor air stability. 2D magnetic metal oxides, which generally exhibit better stability under ambient conditions, represent a promising alternative. In this work, high-quality CoO nanosheets were successfully synthesized via chemical vapor deposition. Structural characterization confirms a well-defined triangular morphology and single-crystalline nature, with the thinnest nanosheets reaching approximately 10.1 nm in thickness. Magnetic measurements reveal significant magnetic anisotropy with an in-plane easy magnetization axis and a transition temperature of approximately 159 K. Our study provides a feasible approach for the controllable synthesis of air-stable 2D magnetic semiconductors, thereby laying a foundation for their potential application in low-power spintronic devices.

Heterogeneously integrated lithium niobate (LN) electro-optic modulators have great potential for high-speed applications, but challenges remain in optimizing performance, particularly in terms of modulation efficiency, bandwidth, and the trade-offs. This work presents an optimized design for a silicon-nitride (Si₃N₄)-loaded modulator on a thin-film lithium niobate (TFLN) platform, consisting of 300 nm-thick LN film and 300 nm-thick Si₃N₄ optical waveguide. By systematically optimizing the dielectric layer thickness, electrode parameters, and achieving velocity and impedance matching, we demonstrate a modulator with a bandwidth exceeding 200 GHz. Our collaborative optimization scheme highlights the critical role of reducing the silicon oxide box layer thickness for velocity matching. We show that multiple structural configurations can achieve bandwidths greater than 120 GHz with V_π·L＜ 4 V·cm, providing feasibility in low-loss design and fabrication. These findings offer valuable design guidelines for high-performance electro-optic modulators suitable for data communications.

Bulk single-crystal aluminum nitride (BSC AlN) substrates are known to be ideal platforms for constructing high-power and DUV optoelectronic nitride devices. However, high-quality epitaxial growth of nitride films on BSC AlN and related characterization is still far from being well studied. The challenges and uncertainties in doing accurate thermal characterization on such heterostructures are not fully recognized. In this study, we successfully fabricated a buffer-free thin GaN/AlN heterostructure on a BSC AlN substrate via metal−organic chemical vapor deposition (MOCVD) technology. This heterostructure consists of a 140 nm-thick AlN homoepitaxial layer and a 480 nm-thick GaN epitaxial layer. Characterization results indicate that the prepared heterojunction has excellent crystal quality and smooth surface morphology. To accurately obtain the thermophysical parameters of the heterostructure, this study employed broadband frequency domain thermoreflectance (BB-FDTR) technology, and careful measurements with detailed data analysis were demonstrated. In addition to showing the feasibility of epitaxial growth of high-quality thin film GaN directly on BSC AlN substrates, this study also provides key experimental data for evaluating the heat dissipation advantages of GaN/AlN heterostructures.

Achieving long-range, high-accuracy depth perception under stringent power constraints remains a critical challenge for stereo vision in edge applications. This work presents a cascadable stereo matching processor that overcomes the inherent trade-off between sensing range and computational efficiency. The core innovation is a scalable semi-global matching (SSGM) algorithm which dynamically optimizes the disparity search range for different baselines, ensuring constant on-chip memory usage and a significant reduction in data movement. The architecture further integrates a raw-domain rectification front-end, which performs direct geometric transformation on Bayer-patterned image streams. This approach eliminates the need for external memory access by bypassing conventional ISP pipelines, thereby maximizing throughput and reducing system memory consumption. Parallel processing paths for multiple baselines converge in a pixel-wise fusion module, which synthesizes a unified depth map by selecting the most reliable disparity estimate for each output pixel. The cascadable stereo matching processor achieves speedups of up to 178x and 97x over CPU and EdgeGPU platforms, respectively, in multi-baseline stereo disparity fusion. Implemented in 40-nm CMOS technology, the processor operates at 160 MHz, achieving a processing speed of 80 frames per second with an energy efficiency of 7.9 pJ/pixel and occupying a core area of 6.04 mm².

We demonstrate room-temperature pulsed lasing of two types of GaN-based surface emitting lasers (SEL) fabricated without epitaxial regrowth. We present a direct comparison between a circular grating (CGSEL) and a photonic crystal (PCSEL) design. The devices are realized by etching the photonic structures directly into the p-GaN cladding, and utilizing a patterned indium tin oxide (ITO) top contact. Both designs exhibit lasing near 438 nm under pulsed current injection. The CGSEL, incorporating a central defect, achieves a low threshold current density (<1 kA/cm²) and a small divergence angle (≈0.15°) by coupling to a bandgap defect mode. In contrast, the PCSEL shows a higher threshold current density and lases on a 1D band-edge mode, resulting in a cross-shaped far-field pattern. These results confirm the regrowth-free method as a viable route for manufacturable GaN SELs. Crucially, the comparative study identifies the CGSEL defect-mode design as a more robust path toward high-performance lasing in low-confinement epitaxial structures.

Temperature dependent photoluminescence (PL) and time-resolved PL (TRPL) of CsPbBr₃ quantum dots (QDs) in solution and film are investigated. The electron−phonon coupling strength of quantum dots in solution is found two times larger than that of thin films. The averaged phonon energy involved in luminescence is also significantly higher than that of thin films, indicating that ligands’ phonons are involved in optical processes in solution but not in film. TRPL shows that the luminescence lifetime of the solution (22.5 ns) is longer than that of the thin film (5 ns) at room temperature, and both decrease abnormally with decreasing temperature, ascribing to the thermally activated trap states for PL, the further analysis shows that the trap energy levels in the thin film are deeper (~20 meV) compared to ~4 meV in solution. Our work proves that the morphology of organic ligands can regulate electron−phonon interactions and optoelectronic properties in CsPbBr₃ QDs, providing fundamental insights into its photophysics.

In fractional-N phase-locked loops, minimizing the integral nonlinearity (INL) of the digital-to-time converter (DTC) is crucial since it directly limits PLL performance. Considering the trade-off between DTC delay range and linearity, this paper presents a fractional-N dual-path SPD/PFD PLL (DP-SPFDPLL) with a complementary DTC pair. Controlled by the complementary control words, two DTCs are introduced before the two inputs of the phase detector for DTC range reduction and INL cancellation. The required DTC range is further halved by using differential VCO outputs to retime the frequency divider output. The overall design collectively achieves a 4× reduction in DTC range requirement. Fabricated in 7 nm FinFET, the DP-SPFDPLL achieves 118 fs RMS jitter and −247.5 dB figure-of-merit.

Battery-free radio systems utilizing wireless power transfer (WPT) further facilitate the miniaturization of neural implants. However, simultaneous monitoring of multiple neuronal activities is required to obtain high-fidelity neural signals. Consequently, the integration of numerous channels on a single chip and the wireless transmission of massive multi-channel data pose significant challenges for implantable battery-free neural interfaces. This work introduces dual overlapped on-chip antennas to eliminate the need for a battery in the neural implants and enable high-data-rate backscatter for transmitting the massive data acquired simultaneously from 72 channels. Additionally, an orthogonal coding and sampling technique is employed to reduce both power consumption and area per channel. Fabricated in a 65 nm CMOS process, the proposed chip integrates 72 neural recording channels within a 2 mm × 2 mm area and achieves a backscatter data rate of 18 Mbps.

This work demonstrates a high-performance vertical GaN p−i−n diode based on a buried p-layer n-p−i−n epitaxial structure. The post-etch magnesium (Mg) diffusion process is applied to suppress the etch-induced surface damage on the p-GaN layer. The Mg diffusion effectively reduces the valence band barrier from 2 to 1.1 eV, yielding a low specific contact resistivity of 6.521 × 10⁻⁴ Ω·cm². As a result, the fabricated devices exhibit markedly enhanced forward characteristics, including a reduced turn-on voltage of 3.3 V and a specific on-resistance of 0.92 mΩ·cm². Temperature-dependent forward I−V measurements indicate that the dominant carrier transport mechanism evolves from defect-related tunneling in the etched devices toward transport dominated by intrinsic p–n junction conduction after Mg diffusion. In addition, the devices exhibit excellent stability in forward conduction, with a voltage variation of approximately 0.028 V. These results indicate that Mg diffusion effectively improves the contact characteristics degraded by ICP etching and provide a viable approach for achieving high-performance and reliable vertical GaN power devices.

Resistive random access memories (RRAMs) are emerging as a key enabling technology for cost-effective, energy-efficient and secure chips, especially in the framework of edge computing. In particular, their electrically programmable resistance has been widely exploited in several in-memory computing and neuromorphic architectures. By adjusting the applied voltages and compliance currents (I_C), RRAM devices can be programmed to multiple resistance states during set and reset procedures, enabling multilevel functionality. While the multilevel behavior of the reset phase is generally well captured by existing compact models, only a few account for the multilevel characteristics of the set operations. Moreover, such models are rarely validated against comprehensive experimental datasets capturing device dynamics across multiple timescales. In this work, we present a physics-based compact model that enhances the UniMORE RRAM framework by incorporating the dynamic lateral evolution of the conductive filament (CF), thereby enabling accurate simulation of set operations at varying I_C values. The model is calibrated to experimental data from IHP 130 nm 1T1R RRAM technology and reproduces device behavior across several operating conditions using a single set of parameters. The results highlight the potential of the proposed compact model in design optimization workflows of RRAM-based circuits.

Al-rich Al_xGa_1−xN (x ≥ 0.8) is promising for power and deep-ultraviolet (DUV) optoelectronic applications, owing to its ultra-wide bandgap and excellent thermal stability. However, forming low-resistivity contacts on n-type Al-rich AlGaN remains a significant challenge. In this work, we utilized an Au-free Ti/Al/Ti metal stack contact on n-type Al-rich AlGaN without graded layers. Record-low contact resistivities were achieved after annealing: 1.52 × 10⁻⁶ Ω·cm² for n-Al_0.8Ga_0.2N, 3.56 × 10⁻⁶ Ω·cm² for n-Al_0.86Ga_0.14N, and 5.79 × 10⁻⁵ Ω·cm² for n-Al_0.9Ga_0.1N. These results demonstrate a significant advancement in forming low-resistance contacts directly on Al-rich n-AlGaN, offering a viable path forward for next-generation power electronics and DUV optoelectronic devices.

In this paper, a compact and low-power sub-THz direct-conversion receiver with a second-harmonic-remixed LO chain is proposed. Based on a common-mode second-harmonic-enhanced network, the common-mode second-harmonic voltage at the drains of the common-source differential pair in the tripler is enhanced and mixed with the fundamental voltage at the gate to generate additional differential third-harmonic voltage. Hence, the saturation output power and efficiency of the triplers used in the LO chain have been significantly improved. The power consumption of the LO chain employed in the receiver is as low as 65 mW. Measurement results demonstrate that the receiver achieves a conversion gain of 30.5 dB and a 3-dB RF bandwidth of 34 GHz, while the in-band minimum noise figure is 9.9 dB.

In this paper, a novel gate-series-diode structure for the Schottky-type p-GaN HEMTs is proposed, and the impact of the proposed structure on gate−source voltage oscillation is investigated when the device is turned on. The proposed structure is capable of effectively mitigating the gate−source voltage overshoot problem of GaN device, and has little effect on the switching characteristics. The gate voltage oscillations can be greatly stabilized at the steady-state turn-on voltage level when the turn-on voltage is 5 V. Compared with the conventional structure, the overshoots of the proposed structure reduce by 31.4%−71.4% and 40.6%−80.4% respectively under the two pulses, as drain−source voltage rises. The proposed structure is proved to be a potential method on improving gate reliability of the most GaN power devices.

LiNi_0.9Mn_0.1O₂ (LNM91) is a promising cobalt-free, high-energy cathode material for next-generation lithium-ion batteries, but its commercialization is challenged by rapid capacity fading resulting from bulk and interfacial structural degradation. Herein, an in situ surface-to-bulk dual-modification strategy is developed to synthesize 6Al-LNM91 (6 mol% Al modified LNM91) via a one-step calcination process based on Al diffusion chemistry. This method concurrently constructs a protective LiAlO₂ coating and incorporates Al³⁺ into the bulk lattice, effectively enhancing the structural integrity of the cathode during cycling. The optimized 6Al-LNM91 cathode delivers a remarkable rate capability of 165 mA∙h∙g⁻¹ at 10 C and maintains 94.03% capacity retention after 120 cycles at 0.5 C (2.8 − 4.4 V), substantially outperforming the pristine material (76.82% of LNM91). This organic solvent-free, single-step modification approach offers a scalable and efficient route for improving high-nickel layered oxide cathodes.

In this letter we report the morphological, electrical and thermal transport properties of a high electron mobility transistor (HEMT) style epitaxial wafer, where an approximately 2000 nm thick GaN layer has been directly deposited on a bulk single crystal AlN (BCS AlN) substrate with no buffer layer in between, and also the experimental results of DC and RF properties of a HEMT device based on such a wafer. The sample achieved very smooth surface morphology and roughness down to Ra = 0.172 nm over an area of 1 μm × 1 μm in AFM measurements. Electrical transport measurements showed sheet carrier concentration of 7.3 × 10¹² cm⁻², Hall mobility of 2220 cm²/(V·s) and sheet resistance of 386 Ω/sq. The measured maximum trans-conductance G_m of the fabricated HEMT device was 250 mS/mm at a gate bias voltage of −1.8 V. With a gate length of 500 nm and a gate-to-drain distance of 4.7 μm, the f_T and f_max, derived from S-parameters measurements, are 25.9 and 54 GHz, respectively. Large-signal RF measurement exhibited a high linear power gain (G_p) of 25.2 dB and a peak output power (P_out) density of 7.2 W/mm@1.5 GHz, associated with a power-added efficiency (PAE) of 40.9%. Comparing with the structure with a 500 nm thick AlGaN buffer, the total thermal resistance of the structure in our device decreased by 44%. This work confirms the technical feasibility of fabricating GaN HEMT devices on BCS AlN substrates without any additional buffer layer, and the excellent electric and thermal transport properties of the simplified wafer structure indicate a bright future of BCS AlN-based GaN HEMT devices in ultra-high-frequency and high-power-density nitride electronics.

This work focuses on the early-life drift mechanisms in 150 nm AlGaN/GaN HEMTs on SiC under RF-HTOL stress at 9 GHz and 130 °C. Electrical measurements during the first hours of stress reveal significant shifts in threshold voltage, transconductance, and drain lag, indicating the activation of deep traps located in the buffer. A transient increase in gate leakage current is also observed under reverse gate bias, suggesting additional trapping or conduction paths at the AlGaN/SiN or cap/passivation interface. These electrical instabilities coincide with a progressive degradation of RF performance, notably in gain and power-added efficiency. Electroluminescence measurements further support the presence of electrically active defects, with distinct spatial patterns depending on the bias configuration.

Fluorescence temperature sensing technology has become a research direction in the field of temperature measurement with its significant advantages of non-contact measurement, high spatial resolution, fast response and anti-electromagnetic interference. Although the double rare earth ion doping ratio fluorescent temperature sensing materials have made significant progress, the thermal quenching phenomenon is still the key bottleneck restricting its performance improvement. In this study, we propose to construct a flexible Sc₂Mo₃O₁₂:Eu³⁺/Tb³⁺ film with negative thermal expansion characteristics, and systematically study its visual temperature sensing characteristics. The negative thermal expansion characteristics of Sc₂Mo₃O₁₂ matrix effectively inhibited the thermal quenching rate of Tb³⁺ luminescence, and enhanced the thermal enhanced luminescence effect of Eu³⁺. This two-way regulation mechanism improves the intensity comparison of the two light-emitting channels, and provides an innovative strategy for improving the sensitivity of temperature sensing. The flexible film based on Eu³⁺/Tb³⁺ codoped system realizes intuitive temperature perception through the significant change of fluorescent color, and can complete the temperature interpretation without complex spectral equipment. This greatly expands its application prospect in the field of rapid field detection and real-time monitoring, and shows its broad potential in the fields of wearable devices, biomedical diagnosis, and real-time monitoring of surface temperature field.

High performance flexible pressure sensors, as a very important group of electronic component for information transmission and collection, have gained widespread attention. Herein, Ti₂CT_x MXene nanosheets were vertically grown on carbon cloth substrate (Ti₂CT_x@CC) via the simple sintering and subsequent etching process. Flexible pressure sensors featuring the Ti₂CT_x MXene nanosheets as the sensitive material were then fabricated using polyvinylidene fluoride (PVDF) film weaved by the electrospinning route between the sensitive material and the interdigital electrodes to improve the sensitivity. As-fabricated flexible sensor exhibited superior performances including high sensitivity up to 3109.2 kPa⁻¹, good response and recovery time of 80/80 ms, and favorable stability over 8000 loading/unloading cycles. Boasting the high sensitivity across a broad range, the sensor can in real-time capture a spectrum of human activities—from the faint pulse signal to the large pressure of joint activities and shows promising capability for mapping spatial pressure distribution.

AlN/GaN high-electron-mobility transistor (HEMT) equipped with ultra-thin AlN barrier epitaxial structures were grown on 6-inch and 8-inch Si-based GaN templates via plasma-assisted molecular beam epitaxy (PAMBE). The AlN barrier thickness was systematically optimized to improve the properties of two-dimensional electron gas (2DEG). Structural and electrical characterizations were performed by atomic force microscopy (AFM), transmission electron microscopy (TEM), contact and non-contact Hall measurements. At an optimal AlN barrier thickness, an extremely low sheet resistance of 159.9 Ω/□ by contact Hall and 143.8 Ω/□ by non-contact Hall was achieved on the 6-inch HEMT wafer, marking a significant improvement over state-of-the-art Si-based GaN HEMTs. The epitaxial surface exhibited excellent morphology with a root-mean-square (RMS) roughness of 0.45 nm. Moreover, cross-sectional TEM analysis of PAMBE-grown AlN/GaN HEMT revealed an atomically sharp and structurally coherent heterointerface, whch is critical for achieving high electron mobility and reduced scattering loss. In addition, the 8-inch HEMT demonstrated a sheet resistance (R_s) as low as 115 Ω/□ by non-contact Hall with a uniformity is 2.13%, outperforming competing technologies than other companies on the market.