Optical properties of atomically thin films of the topological insulator Bi2Se3

Problem formulating. To study the transport properties of atomically thin films of topological insulators, it is very important to determine their thickness as accurately as possible, as well as the state of the surface. Goal. To obtain atomically thin films of the topological insulator Bi2Se3 and to determine their thickness and the degree of surface degradation via their optical properties. Result. A technique that allows one to obtain single-crystal films of large area and various thicknesses on optically transparent substrates has been developed. The dependence of the transparency depending on the number of atomic layers (Bi2Se3 quintiples) in the film is determined. The obtained exact dependence of transparency on the number of layers is in good agreement with theory. It was also possible to observe how the transparency of the films changes over time, which is associated with the degradation of its surface layers. Practical meaning.The results obtained can be used for optical quality control of atomically thin films of quasi-twodimensional compounds, as well as for the manufacture of various micro- and nanostructures based on them, which can bring closer to the creation of a new element base for electronic devices.