Suppressing carrier density in (BixSb1-x)2Te3 films using Cr2O3 interfacial layers

TL;DR

This paper demonstrates that using epitaxial and amorphous Cr2O3 layers as buffer and capping layers in the growth of (BixSb1-x)2Te3 films effectively suppresses carrier density and enhances mobility, advancing topological insulator applications.

Contribution

It introduces a novel interfacial engineering approach with Cr2O3 layers to control carrier density and improve mobility in BST films.

Findings

Carrier density below 10^12/cm^2 achieved across Bi contents.

Higher mobility in BST films with Cr2O3 layers compared to direct growth.

Interfacial layers are crucial for tuning electronic properties of TI films.

Abstract

Band structure engineering and interfacial buffer layers have been demonstrated as effective means to tune the Fermi level in topological insulators (TI). In particular, the charge compensated compound (BixSb1-x)2Te3 (BST) plays a critical role in the molecular beam epitaxy growth of magnetic TIs. Here we introduce a strategy of exploiting epitaxial Cr2O3 as a buffer layer and amorphous Cr2O3 as a capping layer in the growth of BST films. These films exhibit carrier density lower than 1012/cm2 over a wide range of Bi contents and higher mobility than BST films directly grown on Al2O3 substrate, shedding light on the importance of interfacial layers for TI films and paving a new avenue to the application of magnetic BST films.