Probing the semiconductor to semimetal transition in InAs/GaSb double quantum wells by magneto-infrared spectroscopy

TL;DR

This study investigates the transition from semiconductor to semimetal in InAs/GaSb quantum wells using magneto-infrared spectroscopy, revealing spectral evolution and modeling the transition with an eight-band approach, with implications for topological states and terahertz devices.

Contribution

It provides experimental evidence and theoretical modeling of the semiconductor to semimetal transition in InAs/GaSb quantum wells, highlighting control mechanisms and potential applications.

Findings

Spectral evolution from single to multiple absorption peaks with magnetic field.

Successful explanation of absorption peaks using an eight-band Pidgeon-Brown model.

Transition can be controlled via quantum confinement, strain, and magnetic field.

Abstract

We perform a magneto-infrared spectroscopy study of the semiconductor to semimetal transition of InAs/GaSb double quantum wells from the normal to the inverted state. We show that owing to the low carrier density of our samples (approaching the intrinsic limit), the magneto-absorption spectra evolve from a single cyclotron resonance peak in the normal state to multiple absorption peaks in the inverted state with distinct magnetic field dependence. Using an eight-band Pidgeon-Brown model, we explain all the major absorption peaks observed in our experiment. We demonstrate that the semiconductor to semimetal transition can be realized by manipulating the quantum confinement, the strain, and the magnetic field. Our work paves the way for band engineering of optimal InAs/GaSb structures for realizing novel topological states as well as for device applications in the terahertz regime.