Growth of van der Waals topological insulator thin films

Abstract

I will show our results on improving the growth of topological insulator (TI) van der Waals (vdW) thin films using molecular beam epitaxy. First, lattice-matched trivially-insulating buffer layers can be used to reduce the unintentional doing in the films by improving the crystalline quality of the first few TI layers. Second, substrate pre-treatment can reduce twinning and improve TI morphology by satisfying dangling bonds and changing the surface energy. Finally, when TI films are grown on (001) GaAs, the TI film can be grown in an alternate orientation that has an epitaxial relationship to the substrate and that self-assembled TI nano-columns can be grown without the use of strain or catalysts. Despite the weak film-substrate interaction, the morphology and quality of vdW thin films can be strongly controlled by appropriate choice of growth parameters and substrate.