Influence of etching processes on electronic transport in mesoscopic InAs/GaSb quantum well devices

TL;DR

This study compares dry and wet etching processes on InAs/GaSb quantum well devices, revealing differences in electronic width and boundary scattering that impact the study of topological edge states.

Contribution

It provides new insights into how etching methods affect boundary scattering and electronic properties in mesoscopic topological insulator devices.

Findings

Dry etching reduces electronic width with increasing electron density.

Wet etching maintains constant electronic width across densities.

Wet etching results in more specular boundary scattering.

Abstract

We report the electronic characterization of mesoscopic Hall bar devices fabricated from coupled InAs/GaSb quantum wells sandwiched between AlSb barriers, an emerging candidate for two-dimensional topological insulators. The electronic width of the etched structures was determined from the low field magneto-resistance peak, a characteristic signature of partially diffusive boundary scattering in the ballistic limit. In case of dry-etching the electronic width was found to decrease with electron density. In contrast, for wet etched devices it stayed constant with density. Moreover, the boundary scattering was found to be more specular for wet-etched devices, which may be relevant for studying topological edge states.