Unveiling localized electronic properties of ReS₂ thin layers at nanoscale using Kelvin force probe microscopy combined with tip-enhanced Raman spectroscopy

Abstract

The electronic properties of two-dimensional (2D) material is strongly modulated by localized strain. The typical spatial resolution of conventional Kelvin probe force microscopy(KPFM) is usually limited in few hundreds nanometers, which is hard to characterize the localized electronic properties of 2D materials at the nanoscale. Herein, tip-enhanced Raman spectroscopy(TERS) was proposed to combine with KPFM to break this restriction. TERS scan was conducted on ReS2 bubbles deposited on rough Au thin film to obtain strain distribution by using the Raman peak shift. The localized contact potential difference (CPD) was inversely calculated with a higher spatial resolution by using strain measured by TERS and CPD-strain working curve obtained using conventional KPFM and atomic force microscopy(AFM). This method enhances the spatial resolution of CPD measurement and can be potentially used to characterize the localized electronic properties of 2D materials.