Anisotropic Low Schottky Barrier and Transport Properties of the Co-Intercalated Bilayer SnS2/Monolayer SnS2 Junction from First Principles

The high contact resistance at metal/two-dimen-sional (2D) semiconductor junctions is a major issue in nanoelectronic devices. In this work, we proposed and theoretically investigated the transport properties of a SnS2-based field-effect transistor in which a monolayer SnS2 semiconductor is connected to metallic Co-intercalated bilayer SnS2 (Co-SnS2) electrodes. The Co-SnS2/SnS2 junction has a low Schottky barrier height of 0.22 eV in the armchair direction and 0.14 eV in the zigzag direction. Because there are more transport channels in the zigzag direction than in the armchair direction, the former has a higher transmission coefficient than the latter. The Schottky contact can be transformed into an ohmic contact after the bias voltage is greater than 0.3 V for armchair direction and 0.2 V for zigzag direction, as the bottom of the conduction band provides the transport channel. The device also has low contact resistance, which is close to the theoretical limit at 0.6 V bias.