Realizing an Epitaxial Stanene with an Insulating Bandgap

TL;DR

This paper reports the successful growth of epitaxial stanene with an insulating bulk bandgap on PbTe(111) substrates, enabling future studies of topological quantum effects in stanene.

Contribution

The first experimental realization of bulk-insulating epitaxial stanene using PbTe(111) substrates and low-temperature molecular beam epitaxy.

Findings

Stanene grown on PbTe(111) shows characteristic bands with the Fermi level in the bandgap.

Doping Sr in PbTe removes substrate states, resulting in truly insulating stanene.

Progress enables future topological quantum effect studies in stanene.

Abstract

Stanene, a single atomic layer of Sn in a honeycomb lattice, is predicted a candidate wide bandgap two-dimensional (2D) topological insulator and can host intriguing topological states of matter such as quantum anomalous Hall effect and topological superconductivity with different surface modifications. Despite intensive research efforts, one still cannot obtain bulk-insulating stanene samples-a prerequisite for any transport studies and applications of stanene. Here we show the experimental realization of an epitaxial stanene with an insulating bulk bandgap by using PbTe(111) substrates. With low-temperature molecular beam epitaxy, we are able to grow single layer stanene on PbTe(111). In-situ angle-resolved photoemission spectroscopy shows the characteristic stanene bands with its Fermi level lying in the bandgap. Doping Sr in PbTe removes the substrate states located in the stanene gap, resulting in a stanene sample with truly insulating bulk. This experimental progress paves the way for studies of stanene-based topological quantum effects.