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 beta-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 similar to 5.7 eV to similar 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.