Impact of controlling the barrier height on fabrication of high performance β-Ga2O3 solar-blind photodetectors

Abstract

Photodetectors based on Ga2O3 have stimulated extensive attention for diverse applications from civil and military filed. Great progress has been made in the fabrication of Ga2O3-based photodetector, but they still suffer from their low detectivity. In this study, we present an investigation to achieve ultra-low dark current and high detectivity solar-blind for Ga2O3-based photodetector by controlling the defect concentration and interface state well with the pulsed laser deposition method. By using pulsed laser deposition, the stoichiometric multi-component film can be obtained. It has been found that the excellent performances of our device (ultrathin thickness of 47 nm) with a low dark current of pA as well as a high sensitivity of 6.25 × 103 (I photo/I dark) are obtained in the as-grown PD under an oxygen pressure of 50 mTorr. Through high temperature annealing of 800 ° C and high oxygen pressure of 50 mTorr, the fast response speed (a decay time of 15 ms) is achieved. These are attributed to the co-effect of well-controlled high mobility, reduced oxygen vacancy defects in Ga2O3 film and increased Schottky barrier height between metal oxide films and metal contact. The electronic transport mechanism in the devices is described in detail to reveal clearly the influence of gas pressure on the optoelectronic properties of photodetectors, which open a promising direction for the development of high-quality economical products.