Solar-blind ultraviolet photodetectors based on Ta-doped β-Ga2O3 heteroepitaxial films

Abstract

Ta-doped Ga2O3 (Ga2O3:Ta) epitaxial films were grown on SrTiO3 (100) substrates via an MOCVD system. Solar-blind ultraviolet (UV) detectors with a metal-semiconductor-metal structure were fabricated based on the β-Ga2O3:Ta films, and the effects of Ta doping concentration on the photo response were investigated. The surface morphology, composition and band gap of the films were characterized. The β-Ga2O3:Ta UV detectors showed photo response characteristics under 222 nm deep UV light. As the Ta doping concentration increased, the responsivity of the detector increased significantly. For the 1.5 at.% Ta doped UV detector, the responsivity under 222 nm UV light at 8 V bias reached 8.23 A W−1, and the light-dark current ratio is close to 103. Moreover, the responsive rise time (Tr1/Tr2) and decay time (Td1/Td2) at 1 V bias were as short as 0.37 s/0.38 s and 0.41 s/0.85 s, respectively. Ta doping significantly improves the performance of β-Ga2O3 ultraviolet detectors, which may be a feasible method to expand its application potential.