Two-dimensional GeSe-based photodetector with ultra-broadband and polarized light detection

Two-dimensional materials (2D) with internal structural anisotropy have shown great promise in polarized light detection. The typical 2D anisotropy materials, e.g., black phosphorus (BP), is unstable in air, hindering practical application. It is urgent to develop chemically stable and polarization-sensitive materials for photodetectors. Herein, high-quality 2D germanium selenide (GeSe) was synthesized by using a chemical vapor transport and mechanical exfoliation approach. The 2D GeSe exhibits a BP-like structure with in-plane anisotropy, as imaged by scanning tunneling microscopy. This anisotropic property enables it to detect polarized light, since it demonstrated polarization-dependent Raman intensity. Furthermore, photodetectors based on GeSe achieved ultra-broadband spectrum detection ranging from 254 to 1380 nm due to its small bandgap of ∼0.63 eV. This study demonstrates that GeSe is a promising 2D material for stable, broadband, and polarization-sensitive optoelectronic devices.