Measurement of the GaSb surface band bending potential from the magnetotransport characteristics of GaSb–InAs–AlSb quantum wells

Abstract

Low-temperature magnetotransport measurements on GaSb∕InAs∕AlSb coupled quantum well structures with a GaSb cap layer and self-consistent calculations of their electronic structure have led to the determination of the Fermi level at the surface, EFS, of undoped molecular-beam-epitaxy-grown GaSb. EFS is pinned around 0.2eV above the top of the GaSb valence band when the GaSb cap layer width is greater than around 900Å. For smaller GaSb cap widths, EFS decreases with the GaSb width. The undoped GaSb∕InAs∕AlSb heterostructure’s Fermi level is determined by bulk donor defects in the AlSb layer adjacent to the InAs quantum well.

Magneto-infrared modes in InAs-AlSb-GaSb coupled quantum wells

“…The heterostructure's band diagram is shown in Fig.1. The electron density is around 8.6×10 11 cm −2 and the hole density is around 1.2 × 10 11 cm −2 determined by the transport measurement 65 for the particular sample shown in this paper. The electron and hole densities can be determined separately from the SdH oscillations.…”

“…99 The detail configuration of the heterostructure and its corresponding carrier densities can be found in ref. [65]. The electron mobility is around 10 5 cm 2 / V s. 65 The FIR transmission spectroscopy is carried out by a commercial Fourier transform interferometer up to 33 T from 4 K to 45 K using light-pipe optics and a Si bolometer.…”

“…[65]. The electron mobility is around 10 5 cm 2 / V s. 65 The FIR transmission spectroscopy is carried out by a commercial Fourier transform interferometer up to 33 T from 4 K to 45 K using light-pipe optics and a Si bolometer. The magneto-FIR modes are extracted by the ratio of the spectra measured with and without a magnetic field.…”

Self-consistent electronic subband structure of undoped InAs/GaSb-based type II and broken-gap quantum well systems

“…Very recently, we have carried out a systematic experimental study on electronic properties of InAs/ GaSb-based T2BG-QW systems using magnetotransport measurements. 15 Through examining the dependence of electron and hole densities in the system on the thickness of a GaSb cap layer, we found that in an undoped sample structure with a narrow GaSb well layer, the Fermi level of the system is mainly determined by bulk donor defects in the AlSb barrier layer adjacent to the InAs well layer. As the width of the GaSb cap layer increases, the Fermi energy varies slightly due to band bending induced by charge depletion and by the injection of carriers from the cap layer.…”

“…It was demonstrated in the past 10-14 that by solving self-consistently the Schrödinger equation for the eigenfunctions and eigenvalues in conjunction with the Poisson equation for the confinement potential, the self-consistent calculation for electronic subband structure in QW systems can be carried out by taking into account of the effects such as impurity doping, charge distribution, band bending, the presence of a gate voltage, etc. In this article, in conjunction with our very recent experimental findings 15 we develop a transparent approach to calculate self-consistently the electronic subband structure in InAs/GaSb-based type II and brokengap QW systems. From a fundamental perspective, up to now many wellknown features for a conventional QW ͑C-QW͒ remain unknown for a type II and broken-gap QW ͑T2BG-QW͒.…”