Effect of Sn Doping Concentration on the Performance of Ga2O3 Solar-Blind Photodetectors

Abstract Doping engineering has been widely used in semiconductor devices such as Solar-blind Photodetectors. Sn doping due to its low lattice expansion and ability to provide additional charge carriers is an excellent dopant for Ga2O3. However, achieving high-performance Sn-doped Ga2O3 with high film-forming ability is still challenging. In this work, Sn-doped Ga2O3 devices with a metal–semiconductor–metal (MSM) structure were fabricated by Radio Frequency Magnetron Sputtering (RFMS) using stacked targets, which can control doping concentration easily, with a focus on the structural characteristics, compositional properties, and photoelectric performance under different Sn doping concentrations. Sn influences the film quality and electrical conductivity by modulating the internal defects and the substitution ratio of Sn atoms (Sn4+), replacing Ga sites (Ga3+). Through optimization, a device with a Sn doping concentration of 5.45% has achieved a low dark current of 2.3 pA, a high light-to-dark ratio of 1.1 × 105, and a short rise/decay time of 1.84 s/1.56 s. All films consistently exhibited excellent n-type amorphous Ga2O3 characteristics. This result shows that an appropriate Sn doping concentration can achieve a high-performance amorphous Ga2O3 thin film, which provides a valuable reference for the process optimization of Ga2O3.