Enhanced Carrier Transport and Photoresponse in Ga ₂ O ₃ Solar‐Blind Photodetectors via Se‐Induced Valence Band Modulation

Abstract Ga 2 O 3 , with its wide bandgap and excellent physical and chemical stability, has attracted extensive attention for solar‐blind ultraviolet photodetectors. However, intrinsic Ga 2 O 3 devices often face challenges such as slow response times and weak responsivity, which significantly hinder their practical applications. Impurity incorporation modulates the electronic structure of Ga 2 O 3 , facilitating carrier recombination and transport, and thereby enhancing its optoelectronic performance. In the present work, Se doping with varying molar ratios is employed to achieve a continuous tunability of the Ga 2 O 3 bandgap from 4.97 to 4.59 eV. The photodetector performance of the doped devices surpassed that of intrinsic Ga 2 O 3 . Under 5 V at a wavelength of 254 nm, the β ‐Ga 2 (Se x O 1‐x ) 3 ultraviolet photodetector demonstrated a responsivity of 0.78 A W −1 , representing a tenfold enhancement over that of the pure device. The corresponding rise and fall times are 63 and 186 ms, significantly faster than the 182 and 135 ms observed for the pure Ga 2 O 3 device. Se incorporation tailors the valence band structure of Ga 2 O 3 , narrows the bandgap, and enhances carrier transport, collectively boosting photodetector performance. This study demonstrates high‐performance Se‐doped Ga 2 O 3 photodetectors for the first time and provides valuable insights for the design of next‐generation solar‐blind photonic devices.