Ultralow-Noise Nano-Ag/Amorphous Ga2O3 UV Photodetector Realized by Introducing Local Schottky Junctions

An amorphous Ga2O3-based photodetector (PD) generally inevitably suffers from unsatisfactory large dark current due to the high-density defects. Herein, the sporadic Ag nanostructures are innovatively introduced by a facile room-temperature magnetron sputtering technology with a consequent low-temperature annealing process to form scattered local Schottky junctions at the interface between In electrodes and amorphous Ga2O3 film. Because of the construction of Schottky barriers, the obtained In–Ag/amorphous Ga2O3–In metal–semiconductor–metal (MSM) PD achieved an extremely low dark current of 14.7 fA at 5-V voltage and outperformed many other amorphous Ga2O3-based PDs. Under the irradiation of 254-nm ultraviolet light, this PD maintained a large photocurrent of 46.2 nA and exhibited a superior photo-to-dark current ratio (PDCR) of $3.15\times 10^{{6}}$ , an ultrahigh detectivity ( ${D} ^{\ast} $ ) of $2.04\times 10^{{13}}$ Jones, and a good responsivity ( ${R}{)}$ of 14 mA/W at 5-V voltage with 331- $\mu \text{W}$ /cm2 power. The excellent photodetection performance indicates that introducing local Schottky junctions can be an efficient way to reduce dark current without apparently sacrificing photocurrent in MSM-structural PD, which is expected to be promoted to other amorphous semiconductor-based PDs for better performance.