Ultralow-Noise Nano-Ag/Amorphous Ga<sub>2</sub>O<sub>3</sub> UV Photodetector Realized by Introducing Local Schottky Junctions
Lili Yang, Zeng Liu, Qiang Xu, Maolin Zhang, Shan Li, Yufeng Guo, Weihua Tang
Abstract
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.15\times 10^{{6}}$ </tex-math></inline-formula> , an ultrahigh detectivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${D} ^{\ast} $ </tex-math></inline-formula> ) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.04\times 10^{{13}}$ </tex-math></inline-formula> Jones, and a good responsivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}{)}$ </tex-math></inline-formula> of 14 mA/W at 5-V voltage with 331- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> /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.