Far infrared edge photoresponse and persistent edge transport in an inverted InAs/GaSb heterostructure

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.

Anomalous de Haas–van Alphen Effect in InAs/GaSb Quantum Wells

“…We propose that the insulating regime of an electron hole bilayer with a small hybridisa-tion gap is the system of choice. Specifically, InAs/GaSb QWs [15] constitute an ideal platform because they combine a number of desirable features: i) They have an inverted band structure resulting in up-and down-ward dispersing LLs, see Fig.1 whose intersection provides a well-defined closed contour in momentum space; ii) Their dispersion and the band gap are highly tuneable as confirmed by the recent observation of the metal insulator transition [16,17]; iii) They are well described by effective non-interacting models [15]; iv) They have small band masses resulting in sizeable cyclotron frequencies for small magnetic fields such that the AdHvAe should be observable in a broad regime of band gaps; v) In contrast to HgTe QWs [18], which are very difficult to fabri-cate [19], InAs/GaSb QWs are much simpler with many different groups studying the quantum spin Hall properties [16,[20][21][22][23][24][25].…”

Optical response of an inverted InAs/GaSb quantum well in an in-plane magnetic field*

“…This puts a hurdle on the further experimental investigation of the helical edge transport in the InAs/GaSb quantum well system, also on the future quantum device applications. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Many optical experiments have also been carried out in the InAs/GaSb quantum well systems. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In the earlier experiments, the quantum well had a high electron density.…”

Deep subwavelength imaging via tunable terahertz plasmons

“…12 An analogous activity leads to the generation of plasmons in solid-state devices that have many interesting applications in the far-infrared frequency region. [13][14][15][16][17][18][19][20][21][22][23] More importantly, and interestingly, the spatial frequency response of the device can be tuned by varying the gate voltage. 24,25 In this paper, a deep subwavelength imaging technique is proposed where terahertz plasmons, generated by a current in a transistor channel that can be tuned by controlling gate voltage, form the illumination pattern required for SIM.…”