Hybrid reflections from multiple x-ray scattering in epitaxial bismuth telluride topological insulator films

TL;DR

This paper demonstrates a highly precise X-ray diffraction method to characterize interface defects and lattice mismatch in epitaxial bismuth telluride topological insulator films, crucial for optimizing device performance.

Contribution

It introduces a novel approach to accurately measure in-plane lattice mismatches in epitaxial films using hybrid reflections, surpassing previous methods in precision.

Findings

Lattice mismatch of 0.007% was measured with high accuracy.

Hybrid reflections effectively reveal stress relaxation mechanisms.

The method improves defect characterization in topological insulator films.

Abstract

Epitaxial films of bismuth telluride topological insulators have received increasing attention due to potential applications in spintronic and quantum computation. One of the most important properties of epitaxial films is the presence of interface defects due to lateral lattice mismatch since electrically active defects can drastically compromise device performance. By describing hybrid reflections in hexagonal bismuth telluride films on cubic substrates, in-plane lattice mismatches were characterized with accuracy at least 20 times better than using other X-ray diffraction methods, providing clear evidence of 0.007\% lateral lattice mismatch, consistent with stress relaxation associated with van der Waals gaps in the film structure.