Comprehensive Modulation of Conductance Anisotropy in Low-Symmetry ReS2 Transistors

Abstract

The anisotropic nature of the electrical conductance in low-symmetry two-dimensional materials is of great interest for emerging devices, as the existence of anisotropy potentially offers an additional degree of freedom. The comprehensive modulation of the conductance anisotropy in electronic devices is highly desired. However, so far, only tuning of the magnitude has been reported. Here, we report the comprehensive electrical modulation of conductance anisotropy in low-symmetry ${\mathrm{Re}\mathrm{S}}_{2}$ transistors. Device design ensures two comparable processes, i.e., thermionic emission and carrier drift, involved in device transport, which have opposite in-plane anisotropic distributions of conductance. Application of a gate voltage could switch over the dominance between these two processes, therefore, reversing the polarization directions of the maximum conductance. Systematic investigations also show the strong geometrical and temperature dependences of gate modulation. Conductance anisotropy can be tuned from a fourfold difference, with the maximum polarization in the direction of the light effective mass, to a sevenfold difference polarized in the perpendicular direction, i.e., the direction of the heavy effective mass. The demonstrated modulation facilitates the conductance anisotropy as an additional degree of freedom for exploring functionalities for future electronics in low-symmetry semiconductors.