Far Infrared Edge Photoresponse and Persistent Edge Transport in an Inverted InAs/GaSb Heterostructure

TL;DR

This study investigates the edge transport and far infrared photoresponse in an inverted InAs/GaSb heterostructure, revealing robust edge conduction and a photovoltaic response linked to quantum spin Hall edge states.

Contribution

It demonstrates the persistent edge transport and photoresponse in an InAs/GaSb heterostructure, highlighting the coupling of incident radiation to edge states, which is a novel observation.

Findings

Robust edge conduction despite bulk transport.

Strong photovoltaic response at 180 GHz.

Photoresponse linked to quantum spin Hall edge states.

Abstract

Direct current (DC) transport and far infrared photoresponse were studied an InAs/GaSb double quantum well with an inverted band structure. The DC transport depends systematically upon the DC bias configuration and operating temperature. Surprisingly, it reveals robust edge conduction despite prevalent bulk transport in our device of macroscopic size. Under 180 GHz far infrared illumination at oblique incidence, we measured a strong photovoltaic response. We conclude that quantum spin Hall edge transport produces the observed transverse photovoltages. Overall, our experimental results support a hypothesis that the photoresponse arises from direct coupling of the incident radiation field to edge states.