Performance enhancement of solar-blind UV photodetector by doping silicon in β-Ga2O3 thin films prepared using radio frequency magnetron sputtering

Abstract

Si-doped β-Ga2O3 thin films were prepared on c-plane (001) sapphire substrates by radio frequency magnetron sputtering, and then annealed at 800 °C under Ar atmosphere for 1 h. Finally, Metal-Semiconductor-Metal type solar-blind UV photodetectors were prepared using the annealed β-Ga2O3 films. The structure, composition, optical properties and photoelectric detection performance of the films were studied using XRD, EDS, UV–Vis, PL spectroscopy and Keithley-4200 system. Results show that after silicon doping, the preferred orientation of the β-Ga2O3 film varies from (−201) to (200) and (201) crystal planes. EDX and XPS results show that 2.34 at% silicon was doped into Ga2O3 films by substituting Ga atoms. Both XPS and PL results show a decline of defect concentration within the Si-doped films, including oxygen vacancy. Si-doped β-Ga2O3 films exhibit enhanced solar-blind detection performance, with lower dark current (32.2 × 10−12 A) under 15 V bias, higher light-to-dark current ratio (3.2 × 104), higher light power density of 2.4 μW/cm2, and shorter response time. The resultant responsivity, detectivity, and external quantum efficiency are 1.146A/W, 7.14 × 1011Jones, and 5.605 %, respectively, more than one order of magnitude higher than the undoped device. This work indicates that Si is an effective n-type dopant for improving the detection performance of β-Ga2O3 film based solar-blind UV photodetectors.