Transmission Electron Microscopy (TEM) has been considered as a powerful technique to investigate the structural, chemical, and electronic properties of nanomaterials. Recently, the advanced TEM equipped with a spherical aberration corrector was introduced and actively used for uncovering the atomic-scale structure and chemical composition of nanomaterials with various dimensions (from 0D to 3D) in a sub-Å level. In the real materials for various optical, electrical and energy applications, revealing the surface and interface structure is so crucial for improving the performance of future devices. In this case, the cross-sectional TEM analysis combined well-prepared TEM samples should be needed. In this presentation, I will discuss 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, the surface phase separation and reconstruction into graphene and silicon of 4H-SiC by pulsed-laser irradiation is introduced. In addition, metallic 2H phase of niobium disulfide (Nb_1+XS₂) with additional niobium atoms for potential hydrogen revolution reaction (HER) catalysts is clearly visualized via cross-sectional scanning TEM (STEM) images.