Transport properties in asymmetric InAs/AlSb/GaSb electron-hole hybridized systems

Abstract

Transport properties in asymmetric InAs/GaSb and InAs/AlSb/GaSb heterostructures sandwiched by AlGaSb layers were studied. For the InAs/GaSb structures, partially compensated quantum Hall effects arising from the electron-hole hybridization were observed. By changing the thickness of each layer, the energy positions of the conduction band and the valence band can be controlled independently. In InAs/AlSb/GaSb structures, we tried to control the hybridization strength by varying the AlSb barrier thickness. Magnetoresistance measurements, in which the magnetic field was applied perpendicular and parallel to the surface, and cyclotron resonance ͑CR͒ measurements show that there is a clear transition from the electron-hole-hybridized system to the electron-hole-independent system. The transition point appeared at around the 2-nm-barrier thickness in all experiments, suggesting a dominant role of the overlap of electron and hole wave functions. According to the absorption peak shapes in the CR measurements, the hybridized system can be further classified as strongly hybridized or weakly hybridized. Only in the weakly hybridized system was the Shubnikov-de Haas-like oscillation due to the short-range scattering by the hole potential observed in the electron CR absorption peak.

<title>Electronic band structure and semimetal-semiconductor transition in InAs/GaSb quantum wells</title>

“…As a result, both the electron and hole charges coexist in semimetallic structures with thick GaSb layers, while only negative electron charge exists in the InAs layer of a semiconducting structure with a sufficiently thin GaSb layer. This result agrees with the experimental observation [10]. …”

“…Once the electron and hole charge density distributions have been obtained, the Poisson equation is solved taking into account the positive charge of donor defects which are supposed to be ionized. These donor defects as well as the contacts to the InAs/GaSb channel ensure the excess of electrons in the InAs/GaSb quantum wells, observed experimentally [3], [5], [6], [10]. We take the donor defect concentration equal to 2 1 01 1 cm2 at the InAs/GaSb interface for structures investigated experimentally in Ref.…”

Partial hybridisation of electron-hole states in an InAs/GaSb double quantum well heterostructure

“…We now show that in this system there is a coexistence of hole and hybridised electron-hole states, resulting in a quantum transport behaviour that deviates from conventional 2D 13 .…”

Landau-Level Hybridization and the Quantum Hall Effect inInAs/(AlSb)/Suzuki1, Takashina2, Miyashita3 et al. 2004Phys. Rev. Lett.290180View full textAdd to dashboardCite

“…The InAs, AlSb, and GaSb layer thicknesses are 30, 3.6, and 18 nm, respectively. This AlSb thickness is sufficient to render the electron-hole hybridization negligible [10]. Strong R xx oscillations as a function of B are observed as horizontal lines on the plot.…”

“…An InAs=AlSb=GaSb heterostructure sandwiched between Al 0:7 Ga 0:3 Sb barriers is grown on a conductive InAs substrate which acts as a back gate [9]. The inserted AlSb layer takes the role of a barrier between the InAs conduction and GaSb valence bands, controlling the hybridization strength [9,10]. Figure 1(b) shows a contour plot of R xx at 1.6 K as functions of the magnetic field (B) normal to the plane and the gate voltage (V G ) for a sample with a thick AlSb barrier.…”