Anomalous electrical transport in SnSe2 nanosheets: Role of thickness and surface defect states

Abstract

This work examines the influence of thickness on the electrical transport properties of mechanically exfoliated two-dimensional SnSe<inf>2</inf> nanosheets, derived from the bulk single crystal. Contrary to the conventional trend observed in two-dimensional systems, we find a semiconducting to metallic resistivity behavior with decreasing thickness. The analysis of low-temperature conduction indicates an increased density of states at the Fermi level with decreasing thickness, which is further corroborated by gate bias-dependent conductance measurement. The enhanced conductivity in thinner flake is attributed to the n-type doping arising from surface defect states. The presence and evolution of these defect states with thickness are probed by thickness-dependent room-temperature Raman spectroscopy. Our study provides insights into the thickness-dependent electronic transport mechanism of SnSe<inf>2</inf> and the crucial role of defect states in governing the observed conductivity behavior. © (2025), (American Physical Society). All rights reserved.