Surface structures of tellurium on Si(111)-(7x7) studied by low-energy electron diffraction and scanning tunneling microscopy

TL;DR

This study investigates the formation and atomic structure of tellurium layers on Si(111)-(7x7) surfaces using LEED and STM, revealing temperature-dependent surface reconstructions relevant for vdW material epitaxy.

Contribution

It provides detailed experimental insights into the temperature-dependent surface reconstructions of Te on Si(111)-(7x7), including the identification of a (2√3×2√3) R30° structure.

Findings

Amorphous Te layer forms at room temperature.

Weak (7×7) pattern appears at 770 K.

(2√3×2√3) R30° reconstruction observed at 920 K.

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. Bi$_2$Te$_3$. Here, we report the formation of a Te buffer layer on Si(111)$-$(7$\times$7) by low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). While deposition of several monolayer (ML) of Te on the Si(111)$-$(7$\times$7) surface at room temperature results in an amorphous Te layer, increasing the substrate temperature to $770\rm\,K$ results in a weak (7$\times$7) electron diffraction pattern. Scanning tunneling microscopy of this surface shows remaining corner holes from the Si(111)$-$(7$\times$7) surface reconstruction and clusters in the faulted and unfaulted halves of the (7$\times$7) unit cells. Increasing the substrate temperature further to $920\rm\,K$ leads to a Te/Si(111)$-(2\sqrt3\times2\sqrt{3})\rm R30^{\circ}$ surface reconstruction. We find that this surface configuration has an atomically flat structure with threefold symmetry.