Magnetotunneling Between Two-dimensional Electron Gases in InAs-AlSb-GaSb Heterostructures

TL;DR

This paper investigates tunneling magnetoconductance between two 2D electron gases in InAs-AlSb-GaSb heterostructures, revealing how interface quality affects the symmetry of quantum oscillations and conductance behavior.

Contribution

It provides a quantitative model explaining the occurrence of two sets of oscillations and demonstrates how optimizing growth conditions can eliminate asymmetry.

Findings

Two sets of Shubnikov-de Haas oscillations often observed in unoptimized samples.

Optimized interfaces show a single set of oscillations, indicating symmetric electron gases.

The model explains tunneling between Landau levels with different quantum indices.

Abstract

We have observed that the tunneling magnetoconductance between two-dimensional (2D) electron gases formed at nominally identical InAs-AlSb interfaces most often exhibits two sets of Shubnikov-de Haas oscillations with almost the same frequency. This result is explained quantitatively with a model of the conductance in which the 2D gases have different densities and can tunnel between Landau levels with different quantum indices. When the epitaxial growth conditions of the interfaces are optimized, the zero-bias magnetoconductance shows a single set of oscillations, thus proving that the asymmetry between the two electron gases can be eliminated.