High‐Performance Broad‐Spectrum UV Photodetectors with Uniform Response: Engineering β‐Ga <sub>2</sub> O <sub>3</sub> :Si/GaN:Si Heterojunctions via Thermal Oxidation for Optoelectronic Logic Gate and Multispectral Imaging
Jili Jiang, Jiangshuai Luo, Ke Ding, Yan Tang, Hong Zhang, Lijuan Ye, Di Pang, Wanjun Li, Wanjun Li
Abstract
Abstract 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‐Ga 2 O 3 :Si/GaN:Si heterojunction PDs using thermal oxidation, combining the advantages of β‐Ga 2 O 3 :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‐Ga 2 O 3 :Si/GaN:Si heterojunction formation. Uniform Si doping in the β‐Ga 2 O 3 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 × 10 4 A W −1 and a photocurrent‐to‐dark current ratio of 1.3 × 10 5 . 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.