Fermi level tuning and band alignment in Mn doped InAs/GaSb

TL;DR

This paper investigates how Mn doping in InAs/GaSb heterostructures affects Fermi level tuning, band alignment, and introduces paramagnetism, with implications for realizing the quantum anomalous Hall effect.

Contribution

It demonstrates that Mn doping allows Fermi level tuning and impacts band alignment, highlighting the need for precise control to achieve topological insulator states.

Findings

Mn doping enables Fermi level tuning and paramagnetism.

Coexistence of high mobility electron and hole gases observed.

Band bending influences the preservation of topological properties.

Abstract

InAs/GaSb hosts a broken gap band alignment that has been shown to generate helical topological edge states. Upon the introduction of Mn into the structure, it has been predicted to host a quantized anomalous Hall effect. Here, we show that dilute Mn doping on InAs in InAs/GaSb, allows a tuning of the Fermi level, the introduction of paramagnetism, but also has a non-trivial impact on the band alignment of the system. The measurement of Shubnikov-de-Haas oscillations, cyclotron resonance, and a non-linear Hall effect in Mn-doped samples indicate the coexistence of a high mobility two-dimensional electron gas and a hole gas. Conversely, in undoped InAs/GaSb, pure-n-type transport is observed. We hypothesize that Mn acceptor levels can pin the Fermi energy near the valence band edge of InAs, far from the interface, which introduces a strong band bending to preserve the band offset at the InAs/GaSb interface. The realization of the QAHE in this structure will thus require a careful control of the band alignment to preserve topological insulating character.