High-mobility AlAs quantum wells with out-of-plane valley occupation

TL;DR

This study demonstrates high-mobility AlAs quantum wells with out-of-plane valley occupation achieved through advanced growth techniques and strain engineering, significantly improving electron mobility by reducing interface roughness scattering.

Contribution

The paper introduces a novel strain technique to enhance out-of-plane valley occupation and electron mobility in AlAs quantum wells, surpassing previous mobility limits.

Findings

Achieved electron mobility of 8.8 m$^2$/Vs in AlAs quantum wells.

Implemented strain engineering to control valley occupation.

Reduced interface roughness scattering in thicker wells.

Abstract

Employing state-of-the-art molecular beam epitaxy techniques to grow thin, modulation-doped AlAs quantum wells, we have achieved a low temperature mobility of 5.5 m$^2$/Vs with out-of-plane occupation, an order of magnitude improvement over previous studies. However, due to the narrow well width, mobilities are still limited by scattering due to interface roughness disorder. We demonstrate the successful implementation of a novel technique utilizing thermally-induced, biaxial, tensile strain that forces electrons to occupy the out-of-plane valley in thicker quantum wells, reducing interface roughness scattering and allowing us to achieve mobilities as high as 8.8 m$^2$/Vs.