Correlation of Defect Structure and Transport Properties of 2D Materials

prof. Čestmír Drašar

Fakulta chemicko-technologická, Ústav aplikované fyziky a matematiky, Univerzita Pardubice

The type of atoms and the structure they form determine the energy spectra of electrons and phonons, and thus to a large extent the basic physical properties of this structure. Defects associated with doping are typically used to alter charge carrier concentrations, magnetic properties, thermal properties, etc. It is assumed that these defects are homogeneously dispersed, do not interact with each other and their concentrations are temperature independent. This is mostly true for 3D single-element structures. For binary and ternary structures, however, there is more interaction of doping species with native defects, which complicates the situation. This can result in compensation, the formation of complex defects, change in defect concentration with temperature, etc.  For quasi-2D structures the situation is even more complicated. Here, we can encounter a significant formation of larger 2D defects that introduce other more significant changes that are difficult to analyze and usually overlooked. In particular, single crystals of SnSe and Bi₂Se₃ serve as examples of the peculiar behavior ("double" doping, 2D bulk transport properties, superconductivity, Rashba splitting, …) that is associated with structural defects.