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

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.

Anomalously large resistance at the charge neutrality point in a zero-gap InAs/GaSb bilayer

“…At d=10 nm=d c (critical thickness) we obtain E g =0, which corresponds to the boundary between the normal and inverted band structures. Our assignment of these three regimes has also been confirmed by recent infra-red measurements in magnetic fields [31]. In figure 1(b), we report the schematics energy band profiles [26] of the samples in the three regimes.…”

Impact of epitaxial strain on the topological-nontopological phase diagram and semimetallic behavior of InAs/GaSb composite quantum wells

“…Furthermore, we assume a flat potential, neglecting the Hartree potential due to interlayer charge transfer. Since the latter is known to be important for a quantitatively accurate description of the band structure in InAs/GaSb CQWs [21,32], our calculations should be taken as providing a qualitative guide. The influence of the above approximations will be discussed later.…”

“…Specifically, a lattice-mismatched system of InAs/In x Ga 1−x Sb CQWs, in which the In x Ga 1−x Sb layer is under compressive epitaxial strain, has been shown to have an enlarged hybridization gap and thus exhibits significantly reduced residual conduction [17][18][19]. These results remind us of the need to fully take into account the strain effects also in the conventional InAs/GaSb/AlSb system [20,21], termed "the 6.1-A family" [22], that is generally thought of as being approximately lattice-matched. Indeed, Zakharova et al have calculated the band structures of InAs/GaSb CQWs pseudomorphically grown on InAs and GaSb substrates and compared them with that for the unstrained case [20].…”

Structural, morphological and magnetotransport properties of composite semiconducting and semimetallic InAs/GaSb superlattice structure

“…In order to determine the nature of the band structure for the as-grown long-and short-period SL substructures (i.e., semimetallic vs. semiconducting), the electronic band structures for representative InAs/GaSb heterostructures were calculated using an 8-band kÁp model. 34 For this purpose, we consider a two-period InAs/GaSb SL structure confined between two AlSb barrier layers. Each InAs or GaSb quantum well has an identical width, explicitly 7.5 nm or 15 nm, with the AlSb thickness selected accordingly (10 nm and 20 nm, respectively).…”

“…Large body of transport works were devoted to either long or short period InAs/GaSb superlattice structures. 14,16,[34][35][36][37][38][39][40] In this work, we present the synthesis and properties of a double period SL consisting of a short-period SL of 10 InAs/ GaSb repeats embedded into a long-period SL of 4 InAs/GaSb repeats, grown by solid-source MBE. We correlate results with detailed structural analysis and calculated band dispersions computed using an in-house 8 Â 8 kÁp framework.…”