Nanoscale inhomogeneity of the Schottky barrier and resistivity in MoS2 multilayers

Abstract

Conductive atomic force microscopy (CAFM) is employed to investigate the current injection from a nanometric contact (a Pt coated tip) to the surface of MoS2 thin films. The analysis of local current-voltage characteristics on a large array of tip positions provides high spatial resolution information on the lateral homogeneity of the tip/MoS2 Schottky barrier ΦB and ideality factor n, and on the local resistivity ρloc of the MoS2 region under the tip. Here, ΦB=300±24meV, n=1.60±0.23, and ρloc=2.99±0.68Ωcm are calculated from the distributions of locally measured values. A linear correlation is found between the ρloc and ΦB values at each tip position, indicating a similar origin of the ρloc and ΦB inhomogeneities. These findings are compared with recent literature results on the role of sulfur vacancy clusters on the MoS2 surface as preferential paths for current injection from metal contacts. Furthermore, their implications on the behavior of MoS2 based transistors are discussed.