Characterizing the Structure of Topological Insulator Thin Films

TL;DR

This paper investigates the structural defects in topological insulator thin films grown via molecular beam epitaxy, highlighting defect types, their reduction strategies, and implications for film quality and device performance.

Contribution

It provides a detailed analysis of defect formation and mitigation in topological insulator films, offering insights into improving growth processes and device stability.

Findings

Twinned domains are common but can be minimized with specific substrates.

Lattice mismatch induces tilts affecting film quality.

Capping layers help protect films from oxidation.

Abstract

We describe the characterization of structural defects that occur during molecular beam epitaxy of topological insulator thin films on commonly used substrates. Twinned domains are ubiquitous but can be reduced by growth on smooth InP (111)A substrates, depending on details of the oxide desorption. Even with a low density of twins, the lattice mismatch between (Bi,Sb)2Te3 and InP can cause tilts in the film with respect to the substrate. We also briefly discuss transport in simultaneously top and back electrically gated devices using SrTiO3 and the use of capping layers to protect topological insulator films from oxidation and exposure.