On the correlation between the scanning tunneling microscopy image imperfections and point defects of layered chalcogenides 2HMX 2 (M = Mo, W; X = S, Se)

Abstract

Numerous types of image imperfections are found in scanning tunneling microscopy (STM) images of layered transition-metal chalcogenides 2HMX 2 (M = Mo, W; X = S, Se). In an effort to correlate between STM image imperfections and point defects, we carried out a theoretical analysis of how point defects modify the energy spectrum of the ideal defect-free MoS 2 layer in the valence band and conduction band region and what types of image imperfections they lead to. We then surveyed representative STM image imperfections of the 2HMX 2 compounds observed in our study and discussed what types of point defects they might be associated with. Our study shows that, to be able to infer the nature of point defects from observed STM image imperfections, it is essential to carry out controlled experiments from synthesis to STM measurements.