Oxygen vacancies modulating the photodetector performances in ε-Ga2O3 thin films

By acting as the trapping centers during charge carrier transfer, oxygen vacancy (VO) plays a critical role in oxide photoelectric devices. Herein, a post-annealing method was introduced to perfect the photodetection performances of epsilon-Ga2O3 photodetectors (PDs) by improving the film quality and modulating the V-O defect concentration. The native oxygen-deficient epsilon-Ga2O3 epitaxial films fabricated via metal-organic chemical vapor deposition become highly dense and V-O-less after oxidation annealing, leading to an enhanced performance, while they become V-O-rich after reduction annealing to depress the PD property. Compared with the pristine PD, the crucial parameters of the devices with a lower V-O concentration have been improved by 1-6 magnitude with a high photo-to-dark current ratio of 1.06 x 10(8), a large responsivity of 1.368 A W-1, an excellent detectivity of 9.13 x 10(14) Jones, a superior linear dynamic range of 176.7 dB and an outstanding external quantum efficiency of 666.5% and a record-high rejection ratio (R-240/R-400) of 1.80 x 10(7). As the V-O defect is commonly ubiquitous in oxide materials, our investigation of regulating the V-O concentrations in epsilon-Ga2O3 and then exerting influences on the PD capabilities will provide principles for designing high-performance photoelectric devices.