Growth of Topological Insulator Bi2Te3 Ultrathin Films on Si(111) Investigated by Low-Energy Electron Microscopy

The molecular beam epitaxy growth of topological insulator Bi2Te3 thin films on Si(111) substrates has been investigated in situ by low-energy electron microscopy. The crystal structure and surface morphology during growth were directly revealed, which enables us to identify the optimal growth conditions for single crystalline Bi2Te3 films. The formation of thin films is preceded by several surface structures, including a wetting layer and a Te/Bi-terminated Si(111)-1 x 1 reconstruction. Raman scattering spectra and A FM measurements indicate that, under Te-rich conditions, single crystalline films of Bi2Te3 grow along the [111] direction in a layer-by-layer mode. Transport measurements prove the insulating behavior of the films grown in this way.