We report a deep-ultraviolet (DUV) metal-semiconductor-metal (MSM) photodetector based on a β-Ga2O3 thin film deposited by chemical vapor deposition (CVD) on a patterned sapphire substrate (PSS), compared with a control device using a film grown on flat sapphire. To the best of our knowledge, this is the first demonstration of β-Ga2O3 films with a preferred (510) orientation. The film grown on PSS exhibited high defect densities, including structural disorders, oxygen vacancies, and dangling bonds, which enabled exceptional responsivity (106.5 A/W) and specific detectivity (1.36 × 1013 Jones) through strong internal gain and extrinsic transitions, despite a relatively large dark current. A UV/visible rejection ratio (R255/R400) above 104 further confirmed the device's sensitivity. A comprehensive analysis was performed on the impact of defects on the increased dark current and slower response. These findings offer important insights into the growth mechanism of β-Ga2O3 on PSS and highlight its potential for scalable, cost-effective solar-blind photodetectors.

Traditional photodetectors generally have the limitation of single-band detection, making it difficult to effectively distinguish multi-wavelength optical signals. In this study, by constructing a heterojunction structure of Cu2O and alpha-Ga2O3, a photodetection device with wavelength resolution capability was innovatively fabricated. Through the synergistic effect of the built-in electric field of the p-n junction and the semiconductor/electrolyte junction, this detector exhibits unique dual-wavelength response characteristics under 0 V. It generates photocurrents in opposite directions for ultraviolet (UV) light at 255 nm and 365 nm, respectively. Experimental data shows that the responsivity of this device reaches 3.6 mA W-1 under 255 nm UV light and -0.15 mA W-1 at 365 nm. Based on this bidirectional current characteristic, a differential signal encryption communication system was further designed and simulated, effectively avoiding the problem of signal interference in traditional optical communication. The research indicates that photodetectors composed of materials with different band gaps provide an effective way to distinguish different illumination bands, and their bidirectional current characteristics show broad application prospects in the fields of optical communication and optoelectronic devices.

Traditional photodetectors generally have the limitation of single-band detection, making it difficult to effectively distinguish multi-wavelength optical signals. In this study, by constructing a heterojunction structure of Cu₂O andα-Ga₂O₃, a photodetection device with wavelength resolution capability was innovatively fabricated. Through the synergistic effect of the built-in electric field of the p-n junction and the semiconductor/electrolyte junction, this detector exhibits unique dual-wavelength response characteristics under 0 V. It generates photocurrents in opposite directions for ultraviolet (UV) light at 255 nm and 365 nm, respectively. Experimental data shows that the responsivity of this device reaches 3.6 mA W-1under 255 nm UV light and -0.15 mA W-1at 365 nm. Based on this bidirectional current characteristic, a differential signal encryption communication system was further designed and simulated, effectively avoiding the problem of signal interference in traditional optical communication. The research indicates that photodetectors composed of materials with different band gaps provide an effective way to distinguish different illumination bands, and their bidirectional current characteristics show broad application prospects in the fields of optical communication and optoelectronic devices.

We demonstrate a monolithically integrated AlGaN-based ultraviolet (UV) event sensor pixel that detects dynamic intensity changes with 200- mu s temporal resolution at 275-nm wavelength. The device combines AlGaN photodiodes with on-chip event-processing circuitry, achieving 350-mV peak response under 7.8-mW/cm(2) UV illumination. Unlike conventional frame-based UV imaging, this event-driven approach responds instantaneously to intensity variations while eliminating external processing requirements. The demonstrated single-pixel architecture is intrinsically scalable to array-level implementation, establishing a proof-of-concept platform for fully integrated UV event cameras. This breakthrough enables new applications in high-speed motion tracking, real-time UV spectroscopy, and dynamic environmental monitoring.

Quantum dots (QDs) serve as high-performance nanoscale color conversion materials, offering remarkable advantages for full-color micro-light-emitting diode (Micro-LED) displays. However, two critical challenges hinder practical applications: the integration of high-resolution patterned QDs with Micro-LED and the preservation of thermal stability under operational conditions. By the sidewall repair process, the Micro-LED devices can maintain approximately 75% of their performance when the temperature increased from 20 (degrees) C to 100 (degrees) C. Additionally, a systematic investigation into the effect of SU-8 on the luminescent properties demonstrated that integrating QDs with SU-8 offers a promising approach to achieve efficient color conversion without altering electrical performance. These advantages in temperature stability and overall performance also provide critical insights for developing full-color Micro-LED displays.

This paper proposes a back-illuminated separated absorption and multiplication (SAM) structure photodiode based on ferroelectric scandium gallium nitride (ScGaN), which improves the problems of low gain and high operating voltage in conventional gallium nitride (GaN)-based ultraviolet avalanche photodiodes (APDs). Upon introducing an n-type ScGaN interlayer into the device, the strong polarization effect contributes to the enhancement of the built-in electric field. In comparison with conventional p-i-n-i-n GaN-based APDs, the designed back-illuminated device shows a 56% enhancement in avalanche gain to 9.2 × 104 and a decrease in avalanche breakdown voltage from 72 V to 64 V. According to analysis of the internal electric field and band structure, this paper explains the physical mechanism behind the performance enhancement and further optimizes the thickness and doping concentration parameters of the n-ScGaN interlayer. The proper utilization of results will greatly advance ScGaN's potential for future applications in optoelectronic devices.

Strong light absorption in a thin semiconductor film plays a key role in a variety of optoelectronic applications. Most ultrathin absorbers use plasmonic nanocavities or complex nanostructures to maximize absorption, which limits the practical large-scale and the weight efficiency of the device. Here, we show the theoretical and experimental realization of a planar aluminum nitride (AlN) ultrathin film absorber based on a crystallinity-controlled growth strategy. High-quality AlN films were epitaxially grown on single-crystalline aluminum substrates via plasma-enhanced atomic layer deposition (PEALD), with gradual tuning of optical dispersion through engineered crystallinity. Our analysis reveals a systematic evolution in the dispersion relationship as the film thickness increases from 5.5 to 20.5 nm, accompanied by a rise in the refractive index and a clear amorphous-to-crystalline phase transition. By optimizing this transition, a peak absorption efficiency of 98.6% at 157 nm wavelength was experimentally achieved using a 5.5 nm-thick AlN film with a hybrid amorphous-crystalline structure. Concurrently, theoretical numerical simulations project that a near-perfect absorption of 99.9% can be expected at 153 nm with a hypothetical 1 nm single-crystalline AlN heterostructure. This study establishes a scalable, growth-directed strategy for ultra-thin photonic devices, offering a practical route toward high-performance UV optoelectronics without relying on complex meta-structures.

Achieving large-scale, efficient, and sustainable hydrogen production via environmentally friendly photocatalysis requires not only effective mass transfer but also excellent operational stability. Conventional particulate photocatalyst systems suffer from inherent limitations in mass transfer, such as disordered charge carrier migration and uncontrolled gas bubble evolution, which collectively hinder hydrogen production efficiency. Here, we present a new mass transfer strategy for large-scale photochemical hydrogen production, which effectively overcomes intrinsic transport limitations and enables ultra-fast hydrogen bubble detachment by a coalescence-induced jumping mechanism. By rationally designing a tunnel-junction photochemical diode integrated with a micro-basin array of metallic cocatalysts, we achieved nearly 100% activation of surface catalytic sites, thereby promoting directional charge carrier transport and rapid gas bubble evolution. This design delivers an impressive hydrogen production rate of 177.53 µmol h-1 cm-2 and an apparent quantum yield of 70.7% under 420 nm illumination. An outdoor solar-driven photocatalytic reactor (25 cm × 25 cm) with a high hydrogen production rate was successfully demonstrated, validating the performance of a full-scale photocatalyst system. This work demonstrates a large-scale GaN-based photochemical hydrogen-production system and provides a useful structural design strategy for the future development of solar hydrogen-generation technologies.

In the traditional field of GaN-based micro-LED, in order to achieve the goal of highly collimated and directionally emitted linearly polarized light, it is usually necessary to enhance its anisotropy by stacking different optical elements or growing specific photonic crystals. In this research, we put forward an innovative and conduct an in-depth exploration of a structural design that enables the vertical integration of a GaN-based micro-resonant-cavity LED (micro-RCLED) with a functional metasurface. The functional metasurface is meticulously designed to delicately manipulate the collimated emergent light from the resonant cavity. The simulation outcomes demonstrate that the unidirectional luminous performance of the integrated device experiences a remarkable enhancement, the luminous angle evolves from the traditional approximately Lambertian distribution to an extremely narrow angular regime. After integrating independent functional metasurface respectively, the device can achieve control over the focal points, beam deflection angles, and polarization. The findings of this study provide an efficient and feasible solution for the in-depth development of high-performance optoelectronic devices and the innovative exploration of multifunctional light-regulated integrated devices, and hold significant theoretical reference value and practical application value.

Developing multifunctional devices capable of on-demand task switching is crucial for highly integrated intelligent systems. We introduce a multifunctional ultraviolet (UV) photodetector (PD) based on an AlScN/GaN heterojunction, featuring dynamically reconfigurable operating modes via bias voltages. At low bias voltages, it functions as a fast and highly sensitive UV PD (the specific detectivity reaching 9.37x10(12) Jones), applied in high-speed imaging and optical communication. Interestingly, at higher bias voltages, the device exhibits a persistent photoconductivity effect. This behavior enables the effective emulation of biological synaptic plasticity, including key functions such as excitatory postsynaptic current, paired-pulse facilitation, and the transition from short-term memory to long-term memory. Leveraging this unique bias-controlled characteristic, we introduce a hardware-intrinsic encrypted optical imaging scheme by ingeniously combining the device's distinct fast and slow photoresponse dynamics. Secure image access is achieved by employing a combination of synchronized optical inputs and dynamic biasing protocols as security keys. We demonstrate a single AlScN/GaN optoelectronic device platform for achieving reconfigurable multifunctionality and hardware-level encrypted imaging, holding significant potential for neuromorphic computing and highly secure information systems.

In this work, we theoretically simulated the photonic band structures of the proposed photonic crystal based on two-dimensional V-shaped dielectric pillars with the same V-direction and opposite V-direction. The flat-band behavior throughout the entire Brillouin zone was investigated by analyzing the bandwidth variations with optimized parameters and other performances such as electric field distribution and group index. The bandwidth can reach the minimum value of Δωa/2πc=0.00888 and 0.00579 for two cases. The results provide support for searching the flat band throughout the entire Brillouin zone in photonic crystals.

The incorporation of thermal dynamics alongside conventional optoelectronic principles holds immense promise for advancing technology. Here, we introduce a GaON/GaN heterostructure-nanowire ultraviolet electrochemical cell of observing a photothermoelectric bipolar impulse characteristic. By leveraging the distinct thermoelectric properties of GaON/GaN, rapid generation of hot carriers establishes bidirectional instantaneous gradients in concentration and temperature within the nanoscale heterostructure via light on/off modulation. The thermoelectromotive force induced by these gradients, combined with the type-II heterojunction band structure, facilitates carrier transport, resulting in transient bidirectional photothermal currents. The device achieves exceptional responsivity (17.1 mA/W) and remarkably fast speed (8.8 ms) at 0 V, surpassing existing semiconductor electrochemical cells. This bipolar ultraviolet impulse detection mode harnesses light-induced heat for electricity generation, enabling innovative bidirectional encryption communication capabilities. Anticipated applications encompass future sensing, switchable light imaging, and energy conversion systems, thereby laying a foundation for diverse optoelectronic technological advancements. III-V group semiconductor has garnered attention in photothermoelectric field. Here, the authors present a GaON/GaN nanowire-based ultraviolet photothermoelectric detector and describe the physical process of the observed bipolar impulse response.

Photonic crystals have received widespread attention in the field of photonics due to their unique band structures, which can manipulate the propagation of light through periodic dielectric arrangements. Accurate prediction of these band structures is crucial for designing and optimizing photonic devices. However, traditional numerical simulation methods, such as plane wave expansion and finite element methods, are often limited by high computational complexity and long processing times. In this study, we explore the application of the vision transformer (ViT) model to predicting the band structures of photonic crystals efficiently and accurately. To further validate the superiority of the ViT model, we also conduct experiments by using CNN and MLP models on the same scale for band structure prediction. We first generate a dataset of photonic band structures by using traditional numerical simulations and then train the ViT model on this dataset. The ViT model demonstrates excellent learning capabilities, with the loss function value decreasing to as low as 4.42x10(-6) during training. The test results show that the average mean squared (MSE) error of the ViT model predictions is 3.46x10(-5), and the coefficient of determination (R-2) reaches 0.9996, indicating high prediction accuracy and good generalization capability. In contrast, the CNN and MLP models, despite being trained on the same dataset and having the same computational resource allocation, show higher MSE values and lower R2 scores. This highlights the superior performance of the ViT model in predicting the band structures of photonic crystals. Our study shows that the ViT model can effectively predict the band structures of photonic crystals, providing a new and efficient prediction tool for relevant research and applications. This work is expected to advance the development of photonic device design by offering a rapid and accurate alternative to traditional methods.

In this paper, a four-channel demultiplexer based on photonic crystals with an ultra-high quality factor is realized by simulation. The plane-wave expansion and finite element method are used to characterize the photonic band structure and investigate the optical propagation behaviors, respectively. Through optimizing the resonator structure and material parameters, the ultra-high quality factor Q of 9082 can be obtained. Furthermore, using the designed resonator, the average quality factor Q of the four-channel demultiplexer can be realized as high as 8901. In addition, the footprint of the device is 324µm2, the average channel spacing is 0.77 nm, the crosstalk between channels has values from -9.9 to 30.1 dB, and the average transmission is 88.86%. Particularly, the average Δλ is 0.17 nm, which leads to the ultra-high quality factor. The ultra-high quality factor makes the proposed demultiplexer promising for future on-chip optical integration.

In this work, we theoretically investigate the coupling characteristics of optical skyrmions based on localized spoof plasmons (LSPs). First, the single LSP optical skyrmion is realized and resonance modes attributed to different topological features are analyzed. Second, the coupling effect is observed through decreasing the distance between the adjacent LSP optical skyrmions. The coupling LSP optical skyrmions can preserve the topological behaviors, and particularly, three coupling modes (mode-a, mode-b, and mode-c) can be observed. Mode-a presents uniform magnetic field distributions, while mode-b and mode-c can be observed with asymmetric magnetic field distributions. Finally, the ten-coupling LSP optical skyrmions supported by space-coiling cylinders and square structures are realized and the robust topological features are discussed. The results may contribute to the future investigation on designing optical skyrmion crystals and advanced optical devices.

In this article, a κ-Ga2O3 cap layer is introduced as gate dielectric to achieve E-mode GaN p-channel heterostructure FETs (p-HFETs). Due to the high spontaneous polarization of κ-Ga2O3, 2DEG that up to 1.51 × 1014 cm− 2 are induced at the κ-Ga2O3/GaN interface. Based on device simulations, the threshold voltage (VTH) can reach a high value of -2.42 V and maintain negative even when the thickness of the GaN channel (tch) is increased to 50 nm. By interconnecting base and gate to form a double-gate (DG) structure, the control of 2DEG and 2DHG can be realized. The results show that p-HFETs with DG structure not only exhibit a threefold increase in the on-current (ION) while maintaining the E-mode operation, reaching 24.87 mA/mm with VTH of -1.25 V, but also reduce the gate leakage current at forward bias. Furthermore, the utilization of κ-Ga2O3 as the gate dielectric results in an enhancement of the gate breakdown voltage to -35.8 V. The proposed DG p-HFETs represent a promising approach to achieving high-performance enhancement mode p-channel GaN devices.

In this paper, a four-channel demultiplexer based on photonic crystals with an ultra-high quality factor is realized by simulation. The plane-wave expansion and finite element method are used to characterize the photonic band structure and investigate the optical propagation behaviors, respectively. Through optimizing the resonator structure and material parameters, the ultra-high quality factor Q of 9082 can be obtained. Furthermore, using the designed resonator, the average quality factor Q of the four-channel demultiplexer can be realized as high as 8901. In addition, the footprint of the device is 324µm2, the average channel spacing is 0.77 nm, the crosstalk between channels has values from -9.9 to 30.1 dB, and the average transmission is 88.86%. Particularly, the average Δλ is 0.17 nm, which leads to the ultra-high quality factor. The ultra-high quality factor makes the proposed demultiplexer promising for future on-chip optical integration.

The self-powered photoelectrochemical components themselves featured advancements in operating independently without external supply. Ultimately, due to lack of assistance from the external bias, the photoelectrochemical response is commonly restricted by the deficient photo-quantum efficiency for the absence of carrier multiplication. This work demonstrates a self-powered photoelectrochemical photodetector based on CuOx/AlGaN nanowires with staggered band structure and enhanced built-in potential for efficient exciton extraction. The generated multiple excitons within reach-through CuOx layer could be speedily separated before Auger recombination. This yields a 131.5% external quantum efficiency and 270.6 mA W-1 responsivity at 255 nm. The work confirms the role of multiple exciton generation in photoelectrochemical systems, offering a solution on paving path of advance for self-powered optoelectronics and weak-light UV imaging applications.

Broadband and polarization-sensitive photodetection is essential for advanced optical imaging, encrypted communication, and multidimensional sensing. However, achieving simultaneous UV-visible dual-band detection and polarization sensitivity in a single photodetector remains a significant challenge due to material limitations. Herein, a multifunctional photodetector based on a ZrS3/p-GaN 2D-3D heterojunction is demonstrated, integrating the strong ultraviolet (UV) absorption of GaN with the polarization-sensitive visible-light response of ZrS3. The device covers a broad spectral range from UV to visible and exhibits clear polarization sensitivity around 490 nm, which is not achievable with conventional III-V or silicon-based 3D photodetectors. With these features, the device enables dual-band imaging and optical communication. Furthermore, a proof-of-concept application in image encryption and accurate decryption, with a recognition rate of 98 % for the decrypted image, was achieved using polarization as an encryption key and assisted by a convolutional neural network (CNN). This work provides an effective strategy to overcome the functional limitations of conventional photodetectors and presents a promising pathway for developing compact, multidimensional, and intelligent optoelectronic systems.