Spontaneously Oxidized Cu<sub>x</sub>O/β-Ga<sub>2</sub>O<sub>3</sub> p-n Junction for Self-Powered Deep-Ultraviolet Photodetection
Chenyue Zhu, Xi-Shen Guo, Yihang Dai, Zhen Yang, Chunyan Wu, Li Wang, Xiang Zhang, Xiujuan Wang, Lin‐Bao Luo
Abstract
In this work, we demonstrate the fabrication of CuxO/Ga2O3 heterojunction through the spontaneous oxidation of Cu film into CuxO layer during electron beam evaporation. The heterojunction device presents a ultraviolet (UV)/visible rejection ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{{265}}/{R}_{{430}}$ </tex-math></inline-formula> ) at zero bias of 435, enabling the self-powered deep-UV (DUV) photodetection. Upon 265-nm illumination (light intensity: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$21.7 \mu \text{W}\cdot $ </tex-math></inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{2}}$ </tex-math></inline-formula> ), the 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> ) and specific detectivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{D}^{\ast} $ </tex-math></inline-formula> ) reach 0.97 mA <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot \text{W}^{-{1}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.28\times 10^{{10}}$ </tex-math></inline-formula> Jones, respectively. A fast response speed of 5.34/3.64 ms ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\tau _{r}/\tau _{f}$ </tex-math></inline-formula> ) has also been observed, which may ascribe to the fully depleted thin CuxO layer and suggest the ability to detect rapidly switched optical signal. This work sheds light on the facile fabrication of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3-based self-powered DUV photodetectors.