This work presents a novel Gallium Nitride (GaN) high-electron-mobility transistor (HEMT)-based ultraviolet (UV) photodetector architecture that integrates advanced material and structural design strategies to enhance detection performance and stability under room-temperature operation. This study is conducted as a fully numerical simulation using the Silvaco Atlas platform, providing detailed electrothermal and optoelectronic analysis of the proposed device. The device is constructed on a high-thermal-conductivity silicon carbide (SiC) substrate and incorporates an n-GaN buffer, an indium nitride (InN) channel layer for improved electron mobility and two-dimensional electron gas (2DEG) confinement, and a dual-passivation scheme combining silicon nitride (SiN) and hexagonal boron nitride (h-BN). A p-GaN layer is embedded between the passivation interfaces to deplete the 2DEG in dark conditions. In the device architecture, the metal contacts consist of a 2 nm Nickel (Ni) adhesion layer followed by Gold (Au), employed as source and drain electrodes, while a recessed gate embedded within the substrate ensures improved electric field control and effective noise suppression. Numerical simulations demonstrate that the integration of a hexagonal boron nitride (h-BN) interlayer within the dual passivation stack effectively suppresses the gate leakage current from the typical literature values of the order of ${10}^{-8}$ A to approximately ${10}^{-10}$ A, highlighting its critical role in enhancing interfacial insulation. In addition, consistent with previous reports, the use of a SiC substrate offers significantly improved thermal management over sapphire, enabling more stable operation under UV illumination. The device demonstrates strong photoresponse under 360 nm ultraviolet (UV) illumination, a high photo-to-dark current ratio (PDCR) found at approximately ${10}^6$, and tunable performance via structural optimization of p-GaN width between 0.40 μm and 1.60 μm, doping concentration from $5\times {10}^{16}$ ${\mathrm{cm}}^{-3}$ to $5\times {10}^{18}$ ${\mathrm{cm}}^{-3}$, and embedding depth between 0.060 μm and 0.068 μm. The results underscore the proposed structure’s notable effectiveness in passivation quality, suppression of gate leakage, and thermal management, collectively establishing it as a robust and reliable platform for next-generation UV photodetectors operating under harsh environmental conditions.

This study presents a comprehensive simulation-based optimization of gallium nitride (GaN)-based metal–semiconductor–metal (MSM) photodetectors designed for ultraviolet (UV) applications. The proposed device architecture incorporates a novel indium nitride/gallium nitride/aluminum nitride (InN/GaN/AlN) heterostructure integrated on a sapphire substrate, combined with refined doping strategies and interdigitated electrode geometry. By systematically analyzing the effects of mesa layer thickness, buffer layers, substrate type, and doping concentrations, we demonstrate significant enhancements in photocurrent generation, photoabsorption rate, and spectral responsivity. Notably, replacing the conventional sapphire substrate with silicon carbide (SiC) and introducing low-level p-type and n-type (p–n) doping into the GaN region enables p–i–n diode-like behavior, contributing to reduced dark current and improved UV selectivity. Building upon these structural enhancements, the final geometric optimization of the nickel/gold (Ni/Au) electrode fingers led to an approximately eightfold increase in photocurrent compared to the initial design, representing the most significant contribution to the improvement in absorption efficiency. These findings offer an effective route for designing next-generation MSM photodetectors with improved sensitivity, noise performance, and thermal compatibility, suitable for high-performance ultraviolet detection applications.

This work presents a novel Gallium nitride (GaN) high-electron-mobility transistor (HEMT) based ultraviolet photodetector architecture integrating advanced material and structural design strategies to enhance detection performance and stability under room-temperature operation. The device is constructed on a high-thermal-conductivity silicon carbide (SiC) substrate and incorporates an n-GaN buffer, an indium nitride (InN) channel layer for improved electron mobility and two-dimensional electron gas (2DEG) confinement, and a dual-passivation scheme combining silicon nitride (SiN) and hexagonal boron nitride (h-BN). A p-GaN layer is embedded between the passivation interfaces to deplete the 2DEG in dark conditions. Lateral nickel (Ni) source and drain electrodes and a recessed gate positioned within the substrate ensure enhanced electric field control and noise suppression. Numerical simulations demonstrate that the integration of a hexagonal boron nitride (h-BN) interlayer within the dual passivation stack effectively suppresses the gate leakage current from typical literature values of the order of $10^{-7}$~A to approximately $10^{-10}$~A, highlighting its critical role in enhancing interfacial insulation. In addition, consistent with previous reports, the use of a silicon carbide (SiC) substrate offers significantly improved thermal management over sapphire, enabling more stable operation under UV illumination. The device demonstrates strong photoresponse under 360~nm ultraviolet (UV) illumination, high photo-to-dark current ratios (PDCR) of approximately $10^{6}$, and tunable performance via structural optimization of p-GaN width between 0.40~$μ$m and 1.60~$μ$m, doping concentration from $5 \times 10^{16}$~cm$^{-3}$ to $5 \times 10^{18}$~cm$^{-3}$, and embedding depth between 0.060~$μ$m and 0.068~$μ$m.