Single-valley high-mobility (110) AlAs quantum wells with anisotropic mass

TL;DR

This study investigates (110)-oriented AlAs quantum wells, demonstrating single-valley electron occupancy with high mobility and anisotropic effective mass, supported by experimental transport measurements and theoretical calculations.

Contribution

It provides experimental evidence of single-valley occupancy in (110) AlAs quantum wells with high mobility and confirms theoretical predictions about valley occupancy and anisotropic mass.

Findings

Observed mobility anisotropy ratio of 2.8 along different crystallographic directions.

Confirmed single-valley occupancy for well widths greater than 53 Å.

Supported experimental results with strain and quantum confinement calculations.

Abstract

We studied a doping series of (110)-oriented AlAs quantum wells (QWs) and observed transport evidence of single anisotropic-mass valley occupancy for the electrons in a 150 \AA wide QW. Our calculations of strain and quantum confinement for these samples predict single anisotropic-mass valley occupancy for well widths $W$ greater than 53 \AA. Below this, double-valley occupation is predicted such that the longitudinal mass axes are collinear. We observed mobility anisotropy in the electronic transport along the crystallographic directions in the ratio of 2.8, attributed to the mass anisotropy as well as anisotropic scattering of the electrons in the X-valley of AlAs.