Room-Temperature Near-Infrared and Self-Powered Photodetectors Based on Graphite/WTe<sub>2</sub>/Ge Mixed van der Waals Heterostructure
Hengyi Li, Jianming Huang, Peng Gao, Baoxiang Yang, Zhibin Lan, Wei Gao, Feng Zhang, Mengmeng Yang, Zhaoqiang Zheng, Nengjie Huo, Jingbo Li
Abstract
Herein, we report a graphite (Gr)/WTe2/Ge mixed-dimensional van der Waals (vdWs) heterojunction-based Schottky photodetector (PD) for self-powered near-infrared detection. Notably, the fabricated device can respond to the wide spectrum of 400–2200 nm with the optimal wavelength around 1550 nm. In particular, it exhibited remarkable photovoltaic characteristics with a maximum responsivity of 2.3 A/W, a specific detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.4\times 10^{{10}}$ </tex-math></inline-formula> Jones, and a light <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ </tex-math></inline-formula> ratio of over <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{3}}$ </tex-math></inline-formula> with a fast response speed of 4.4/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8.6 \mu \text{s}$ </tex-math></inline-formula> under 1550 nm. Moreover, a clear single-point image of “SCNU” in the self-driven mode can be obtained under 1550 nm illumination. The above results suggest that the constructed Gr/WTe2/Ge PD shows great potential in the field of ultrafast near-infrared detection and high-resolution imaging.