High‐Performance Broad‐Spectrum UV Photodetectors with Uniform Response: Engineering β‐Ga ₂ O ₃ :Si/GaN:Si Heterojunctions via Thermal Oxidation for Optoelectronic Logic Gate and Multispectral Imaging

Developing high-performance, broad-spectrum ultraviolet photodetectors (PDs) with uniform response is crucial for optoelectronic applications like spectral analysis, optoelectronic logic gates, and multispectral imaging. This study constructs n-n type β-Ga₂O₃:Si/GaN:Si heterojunction PDs using thermal oxidation, combining the advantages of β-Ga₂O₃:Si and GaN:Si for excellent broad-spectrum response (UV-A to UV-C). A proposed channel model for GaN:Si oxidation includes hole formation, vortex structure development, channel formation, and grain growth, providing a basis for understanding β-Ga₂O₃:Si/GaN:Si heterojunction formation. Uniform Si doping in the β-Ga₂O₃ layer, achieved through thermal oxidation, reduces resistivity, enhances the collection of photogenerated carriers from the underlying GaN layer, and hence enhances broad-spectrum response performance. The devices exhibit outstanding uniformity and sensitivity across the UV-A to UV-C range, with a peak responsivity of 2.44 × 10⁴ A W^-1 and a photocurrent-to-dark current ratio of 1.3 × 10⁵. Applications include optoelectronic logic gates executing "OR gate" and "AND gate" logic operations with 254 and 365 nm UV light, and a single-pixel multispectral imaging system producing high-contrast, clear "CNU" images with 254, 295, and 365 nm UV light. This research advances the understanding of oxide heterojunction formation and offers a method for developing high-performance, uniformly responsive broad-spectrum UV photodetectors for optoelectronic applications.