Surface structures of tellurium on Si(111)–(7×7) studied by low-energy electron diffraction and scanning tunneling microscopy

Abstract

The Te-covered Si(111) surface has received recent interest as a template for the epitaxy of van der Waals (vdW) materials, e.g. Bi2Te3. Here, we report the formation of a Te buffer layer on Si(111)–(7×7) by low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). While deposition of several monolayer (ML) of Te on the Si(111)–(7×7) surface at room temperature results in an amorphous Te layer, increasing the substrate temperature to 770 K results in a weak (7×7) electron diffraction pattern. Scanning tunneling microscopy of this surface shows remaining corner holes from the Si(111)–(7×7) surface reconstruction and clusters in the faulted and unfaulted halves of the (7×7) unit cells. Increasing the substrate temperature further to 920 K leads to a Te/Si(111)–(23×23)R30° surface reconstruction. We find that this surface configuration has an atomically flat structure with threefold symmetry.