Two-dimensional (2D) materials and heterostructures exhibit exceptional electronic, optical and chemical properties, promising to find applications ranging from electronics and photovoltaics to quantum information science. However, the exceptional properties of these materials strongly depend on their 3D atomic structure especially crystal defects. Using Re-doped MoS2 as a model, we developed scanning atomic electron tomography (sAET) to determine the atomic positions and crystal defects such as dopants, vacancies and ripples with a 3D precision down to 4 picometers. We measured the full 3D strain tensor and quantified local strains induced by single dopants. By directly providing experimental 3D atomic coordinates to density functional theory (DFT), we obtained more realistic electronic band structures than those derived from conventional DFT calculations relying on relaxed 3D atomic models. We anticipate that sAET is not only generally applicable to the determination of the 3D atomic coordinates of 2D materials, heterostructures and thin films, but also could transform ab initio calculations by using experimental atomic coordinates as direct input to reveal physical, material, chemical and electronic properties.

Published in: "arXiv Material Science".