High-performance polarization-sensitive photodetectors on two-dimensional beta-InSe

Two-dimensional (2D) indium selenide (InSe) has been widely studied for application in transistors and photodetectors, which benefit from its excellent optoelectronic properties. Among the three specific polytypes (gamma-, epsilon- and beta-phase) of InSe, only the crystal lattice of InSe in beta-phase (beta-InSe) belongs to a non-symmetry point group of D-6h(4), which indicates stronger anisotropic transport behavior and potential in the polarized photodetection of beta-InSe-based optoelectronic devices. Therefore, we prepare the stable p-type 2D-layered beta-InSe via temperature gradient method. The anisotropic Raman, transport and photoresponse properties of beta-InSe have been experimentally and theoretically proven, showing that the beta-InSe-based device has a ratio of 3.76 for the maximum to minimum dark current at two orthogonal orientations and a high photocurrent anisotropic ratio of 0.70 at 1 V bias voltage, respectively. The appealing anisotropic properties demonstrated in this work clearly identify beta-InSe as a competitive candidate for filter-free polarization-sensitive photodetectors.