Thermal annealing effect on β-Ga2 O3 thin film solar blind photodetector heteroepitaxially grown on sapphire substrate

This paper presents the effect of thermal annealing on β-Ga2O3 thin film solar-blind (SB) photodetector (PD) synthesized on c-plane sapphire substrates by a low pressure chemical vapor deposition (LPCVD). The thin films were synthesized using high purity gallium (Ga) and oxygen (O2) as source precursors. The annealing was performed ex situ the under the oxygen atmosphere, which helped to reduce oxygen or oxygen-related vacancies in the thin film. Metal/semiconductor/metal (MSM) type photodetectors were fabricated using both the as-grown and annealed films. The PDs fabricated on the annealed films had lower dark current, higher photoresponse and improved rejection ratio (R250/R370 and R250/R405) compared to the ones fabricated on the as-grown films. These improved PD performances are due to the significant reduction of the photo-generated carriers trapped by oxygen or oxygen-related vacancies.