Advanced interface analysis of 2D-TMD materials using cross-sectional transmission electron microscopy

Abstract

Transmission Electron Microscopy (TEM) has been considered as a useful technique to investigate the structural, chemical, and electronic properties of two-dimensional transition metal dichalcogenides (2D-TMDs). Especially, the advanced scanning TEM (STEM) equipped with a spherical aberration corrector was introduced and actively used for uncovering the atomic-scale structure and chemical composition of 2D materials in a sub-Å level. In the real electronic devices and catalytic systems, revealing the surface and interface structure found at the regions between metal and 2D material or among different 2D materials is so crucial for improving the performance. In this case, the cross-sectional TEM analysis combined well-prepared TEM samples is needed. In this presentation, I will present various cross-sectional (S)TEM works which were performed using a Cs corrected (S)TEM combined with a focused ion beam (FIB) sample preparation technique. Firstly, I will show the unique interface analysis which are important for characterizing the fundamental phenomena found at the interface between metal (In/Au alloy) and 2D monolayer MoS2 using field-effect transistors. In addition, metallic 2H phase of niobium disulfide (Nb1+XS2) with additional niobium atoms for potential hydrogen revolution reaction (HER) catalysts is clearly visualized via cross-sectional scaning TEM (STEM) images.