Dabing Li

In-sensor computing enables real-time and intelligent analysis with superior energy efficiency. However, existing oxide-based or 2D-ferroelectric-based in-sensor computing devices suffer from severe response loss and challenges in large-scale fabrication. Here a III-nitride-based in-sensing computing device is proposed by exploiting its intrinsic polarization effects in their heterostructures. The polarization-induced spatial separation of photogenerated carriers and the defect-free nature of bipolar polarization interfaces effectively avoid carrier recombination losses, enabling high light sensitivity level of nanowatt per square centimetre, responsivity level of 10⁶A W⁻¹ and on/off ratio level of 10⁵ in the sensor-memristor mode. Additionally, controlled applied bias allows the sensor-memristor to transform into a high-speed detector. These results establish a viable design principle that utilizes interfacial-electrostatics-induced photocarrier spatial separation and asymmetric-barriers-modulated carrier transport to realize in-sensor computing. Moreover, the high-temperature resistance of III-nitrides allows the device to maintain high performance at temperatures up to 300 °C. This approach aligns with industrial-scale III-nitride manufacturing and complementary metal–oxide–semiconductor integration, probably advancing the feasibility of in-sensor computing architectures.

The n-doping of Al-rich AlGaN with Al content over 80% remains a crucial challenge for the advancement of far-ultraviolet C (far-UVC) optoelectronic devices. Although low-temperature growth can improve electrical performance by suppressing defect compensation, it will deteriorate the surface morphology and impede the subsequent epitaxy. Particularly for n-AlGaN grown on high-temperature-annealed AlN/sapphire (HTA-AlN) templates, which usually exhibit strong compressive stress, the significant compressive stress accumulated within n-AlGaN will further hamper the formation of a smooth surface. To address this issue, we propose a strain engineering strategy for n-AlGaN growth by metalorganic chemical vapor deposition (MOCVD) at a relatively low temperature of 1075 °C, facilitating step-flow growth while maintaining high electrical conductivity. Nearly stress-free AlN templates were obtained through TMAl pretreatment of the HTA-AlN templates, reducing the in-plane compressive strain of the epitaxial n-AlGaN layer from 0.74% to 0.44%. This strain relaxation drives a distinct morphological evolution of the epitaxial n-AlGaN from three-dimensional hillocks to step-terrace structures, significantly reducing the surface roughness. The strain-modified Burton–Cabrera–Frank model indicates that relieving compressive strain can reduce the maximum surface supersaturation, facilitating step-flow growth of epitaxial n-AlGaN at the low-temperature window. Ultimately, an epitaxial n-Al0.8Ga0.2N with a step-flow surface exhibits a conductivity of 34.1 S/cm, and its application in far-UVC light-emitting diodes demonstrates its effectiveness. This strain engineering strategy provides a promising pathway for the low-temperature growth of Al-rich n-AlGaN by MOCVD on HTA-AlN templates with strong compressive stress, advancing their application in far-UVC optoelectronic devices.

Ultraviolet (UV) light has unique properties that make it valuable in nature and technology, driving the development of UV optoelectronics. Compact, high-performance UV optoelectronic devices such as emitters, detectors, and switches are critical for diverse applications, including surface and air disinfection, bioluminescent agent detection, and secure communications. Wide-bandgap (WBG) semiconductors are fundamental to UV optoelectronic devices due to their broad and tunable bandgaps. This roadmap systematically outlines the current status of WBG materials (including bulk AlN substrates, AlGaN alloys, SiC, and β-Ga₂O₃) and their state-of-the-art UV devices. Since 2020, UV devices, especially emitters, have made remarkable progress. The best commercially available UVC-LEDs around 265 nm exhibit wall-plug efficiency near 10% and L70 lifetimes of more than 10,000 hours. An urgent need to inactivate pathogenic microorganisms has significantly accelerated the development of far-UVC LEDs, particularly during the COVID-19 pandemic. Currently, far-UVC LEDs emitting below 240 nm achieve wall-plug efficiencies exceeding 1%. Additionally, room-temperature continuous-wave lasing has been demonstrated from an AlGaN-based UVC laser diode near 274 nm. Despite these advancements, development remains constrained by material growth challenges (e.g., substrate quality, p-type doping, and defect control) and device-level limitations (e.g., high operating voltage, low output power, limited efficiency, and inadequate lifetimes). Therefore, this review also discusses key challenges in material growth, device fabrication, and reliability, and proposes targeted technological advancements to guide the development of next-generation technologies that meet evolving market requirements.

Hot‐carrier cooling asymmetry is a fundamental bottleneck in polar III‐nitride quantum wells, driving electron leakage and limiting radiative efficiency in light‐emitting devices (LEDs). Here we uncover a defect‐enabled strategy to symmetrize carrier relaxation in InN/GaN quantum wells by engineering nitrogen vacancies (V _N ) at the N‐polar (000‐1) interface. First‐principles calculations combined with ab initio nonadiabatic molecular dynamics reveal that pristine InN/GaN exhibits markedly slow electron cooling due to sparse conduction‐band states and weak electron‐phonon coupling, whereas holes relax rapidly. Interfacial V _N introduces multiple localized electronic levels above the CBM that bridge the low‐density of states (DOS) gap, concurrently increasing local electronic‐state continuity and strengthening nonadiabatic (electron‐phonon) coupling. As a result, hot‐electron cooling is accelerated by up to ∼8‐times (from 9.22 to 1.05 ps), approaching balanced relaxation with holes (0.58 ps). Parameterized TCAD (Technology Computer‐Aided Design) simulations further illustrate that stronger phonon‐assisted scattering suppresses electron leakage in a simplified InN/GaN LED model. This work establishes point‐defect engineering as an effective pathway to control hot‐carrier relaxation and improve carrier balance in polar semiconductor heterostructures.

Gallium nitride (GaN) power devices grown on silicon (Si) substrates have attracted strong interest. The GaN-on-Si platform offers a cost-effective and scalable route for next-generation power conversion. This approach combines the superior material properties of GaN with the manufacturing advantages of Si. GaN provides a wide band gap (3.4 eV), high electron velocity, and a large critical breakdown field. Si enables large wafer size and mature device processes. However, GaN-on-Si technology remains challenging in fundamental device physics and device modelling. Essential issues include high-density lattice-mismatch-induced defects, significant defect-induced leakage current, nonuniform electric field profile, and increased dynamic specific on-resistance ( R _on,sp ). To address the critical challenges and propose device remedies, this article reviews recent advances for GaN-on-Si power devices with high Baliga’s figure of merit (BFOM) and well-developed simulation models. The impact of material defects/dislocations on the current leakage mechanism and device reliability is discussed. Different junction termination strategies for GaN power devices are also summarized, with emphasis on increasing the breakdown voltage and interpreting the relevant device physics. In order to understand the underlying essence for the increased BFOM, important factors and the governing device physics for R _on,sp are systematically analysed, respectively. Finally, with a better understanding of GaN-on-Si power devices, we report the strong requirement for developing the physical models so that the revised impact ionization and carrier transport models have been developed and presented in this work.

Artificial olfactory sensors have garnered significant attention in various applications, including micro‐robotics, implantable medical devices, and consumer electronics. However, they still face challenges in trade‐offs among high recognition accuracy, compact size, and low power consumption. Existing strategies can rely on large‐scale sensor arrays (up to 10 ⁴ elements) to enhance gas recognition accuracy, but this substantially increases system size and power consumption. Inspired by biological multisensory synergy, we propose a visual–olfactory bimodal neuromorphic device to overcome these limitations. It emulates biological perceptual fusion, including bimodal perceptual weighting and enhancement. With a small active area of 148 µm ² , a static power consumption of only 3.4 µW, and a low operating voltage of 1 V, the device exhibits ppb‐level sensing performance and is capable of both classifying gas types and identifying concentrations for multiple target gases. The proposed bimodal perception strategy achieves a gas classification accuracy of 98.27%, far exceeding that of the olfactory unimodal mode (52.24%), and, importantly, enables precise discrimination of mixed gases with highly overlapping sensing signatures. Our strategy not only provides a unit architecture for constructing miniaturized, low‐power, and highly accurate artificial olfactory systems but also paves the way for next‐generation bio‐inspired multimodal neuromorphic sensing.

The integration and miniaturization of chips lead to significant power consumption and heat accumulation. Typically, the energy consumption of cooling systems accounts for morn than 50% of the input energy. Current thermal management technologies do not offer solutions for on-chip thermal energy loss. Herein, we propose an on-chip integrated thermal recovery system, which can simultaneously achieve efficient heat dissipation. Present system on chips is based on hydrovoltaic generator technology, consisting of electrodes and gel. With the deep ultraviolet LED (236 nm) chip suffering from severe heat accumulation as a prototype, upon integration with the thermal recovery system, not only maintain the chip temperature below 40 °C, but also converts waste heat into stored electrical energy, resulting in a 610.70% improvement in overall energy utilization efficiency. To demonstrate its general applicability in commercial CPU systems, we used the commercial Intel G3220 chip and as an example, by incorporating four HEG units, the temperature was reduced from 93 °C to below 60 °C, effectively enhancing computational performance and extending the chip’s lifespan.

AlGaN-based distributed-feedback (DFB) laser diodes (LDs) operating at 280 nm and incorporating surface gratings with different phase shifts were designed and investigated. Compared to Fabry–Pérot (FP) and other phase-shifted designs, the DFB LD with a 1/4 phase shift exhibits the best performance, achieving a threshold current of 17.39 mA (25.4% lower than FP), a slope efficiency of 1.254 W/A (411.1% of FP), and a side-mode suppression ratio of 25 dB at 0.10 A. Systematic analysis reveals that the 1/4 phase shift introduces a localized defect mode at the stop band center, thereby lifting Bragg-mode degeneracy and strengthening longitudinal-mode selectivity, leading to a significant improvement in slope efficiency. Furthermore, scattering-loss analysis indicates that the design can tolerate a dislocation density of up to 2.2 × 109 cm−2, highlighting fabrication feasibility on AlN/sapphire substrates. This design outlines a promising route toward low-threshold, high-power, single-mode, and cost-effective AlGaN Deep-ultraviolet DFB LDs.