Al xIn 1− xAs 1− ySb y/GaSb effective mass superlattices grown by molecular beam epitaxy

Abstract

A detailed study of the growth of Al x In 1− x As 1− y Sb y /GaSb multilayers on GaSb(1 0 0) substrates by molecular beam epitaxy (MBE) has been performed as part of an investigation for the use of this materials system for kinetic heterojunctions (KHJs). KHJs exploit kinetic energy variations brought about by an effective mass discontinuity across the junction. Multiple kinetic heterojunctions or effective mass superlattices (EMSs) are predicted to exhibit unique features, such as equally spaced subbands, not found in conventional superlattices which may lead to a new generation of devices based on kinetic confinement rather than potential confinemnet. Al x In 1− x As 1− y Sb y /GaSb EMSs were synthesized by MBE focusing on tailoring the composition such that there is a zero conduction band offset at the Γ point, a zero modulation of the electron affinity and lattice matching across the heterojunction facilitating studies of purely kinetic effects. This is achieved when x= y≅0.5, which lies in the center of the predicted miscibility gap, therefore a detailed study of the growth of the quaternary has been performed. High-quality EMSs were grown in the range ( 0.3⩽x⩽0.6, 0.5⩽y⩽1.0 ) as assessed by X-ray diffraction. Magneto-transport measurements were performed to determine layer mobility and conductivity. Shubnikov–de Haas (SdH) analyses were performed to verify two-dimensional carrier confinement.