Growth and characterization of Sn-doped β-Ga2O3 thin films by chemical vapor deposition using solid powder precursors toward solar-blind ultraviolet photodetection

In this study, Sn-doped β-Ga2O3 thin films were successfully grown by selecting stable, solid and nontoxic mixed powders (SnO2, Ga2O3 and graphite) as precursors during chemical vapor deposition in a cheap and traditional tube furnace reactor. By doping more Sn, optical bandgap of the films obviously shifted from ~5.7 eV to ~5.2 eV. At 50 V, the dark current of metal-semiconductor-metal solar-blind ultraviolet (UV) photodetectors increased from 0.04 pA to 2.57 pA as more Sn was doped, along with the improved responsivity from 0.2 mA/W to 80 mA/W and reduced decay time from 0.207 s to 22 ms, which may be ascribed to much faster transit time from lower boundary barrier in a grain-boundary related transport process. In comparison with the devices on Sn-doped Ga2O3 thin films by expensive MBE, our photodetectors with comparable responsivity show advantages of much lower dark current and faster decay time, which may provide a cheap and easy way to investigate their application for solar-blind UV photodetectors.