Flexible UV Detectors Based on in-situ Hydrogen Doped Amorphous Ga2O3 with High Photo-to-dark Current Ratio

Amorphous Ga2O3 (a-Ga2O3) has been attracting more and more attention due to its unique merits such as wide bandgap (~4.9 eV), low growth temperature, large-scale uniformity, low cost and energy efficient, making it a powerful competitor in flexible deep ultraviolet (UV) photodetection. Although the responsivity of the ever-reported a-Ga2O3 UV photodetectors (PDs) is usually in the level of hundreds of A/W, it is often accompanied by a large dark current due to the presence of abundant oxygen vacancy (VO) defects, which severely limits the possibility to detect weak signals and achieve versatile applications. In this work, the VO defects in a-Ga2O3 thin films are successfully passivated by in-situ hydrogen doping during the magnetron sputtering process. As a result, the dark current of a-Ga2O3 UV PD is remarkably suppressed to 5.17×10-11 A at a bias of 5 V. Importantly, the photocurrent of the corresponding device is still as high as 1.37×10-3 A, leading to a high photo-to-dark current ratio (PDCR) of 2.65×107 and the capability to detect the UV light with the intensity below 10 nW/cm2. Moreover, the H-doped a-Ga2O3 thin films have also been deposited on polyethylene naphtholate (PEN) substrates to construct flexible UV PDs, which exhibit no great degradation in bending states and fatigue tests. These results demonstrate that hydrogen doping can effectively improve the performance of a-Ga2O3 UV PDs, further promoting its practical application in various areas.