Room-Temperature Near-Infrared and Self-Powered Photodetectors Based on Graphite/WTe2/Ge Mixed van der Waals Heterostructure

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 $3.4\times 10^{{10}}$ Jones, and a light ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio of over $10^{{3}}$ with a fast response speed of 4.4/ $8.6 \mu \text{s}$ 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.