Two-dimensional electron gas formed in a back-gated undoped heterostructure

Abstract

By using a back-gate operation, a high-quality two-dimensional electron gas (2DEG) is formed in an undoped GaAs/AlGaAs inverted heterostructure. A high mobility of around 3×106 cm2/V s at 1.6 K is obtained for the structure without any compensating surface doping. The electron density is controllable down to 7×109 cm−2. The relation between electron density and mobility is studied for samples both with and without a surface gate. The obtained results indicate that background impurities and an inhomogeneity of the electric field coming from the surface govern the mobility in a low-electron-density region and that the interface inhomogeneity becomes important at a high electron density.

Exchange energy enhancedg-factors obtained from Landau fan diagrams at low magnetic fields

“…Gated undoped GaAs/Al x Ga 1−x As QWs are suitable for such investigations because of low disorder in the low electron density regime due to the lack of a donor layer and the ability to tune the electron density from nominally zero to the order of 1 × 10 11 cm −2 by gate voltage. 9,16,17 In this paper, we report on systematic PL measurements of a gated undoped GaAs/Al x Ga 1−x As QW sample in low electron density below 1 × 10 11 cm −2 in low perpendicular magnetic field B 1 T, where the spin-split energy of a valence band hole is linear in B in good approximation. 11 The Landau fan diagrams are obtained from the circular polarization resolved PL peaks.…”

Linear scaling calculation of ann-type GaAs quantum dot

“…The Fermi-energy (E F ) is taken as the origin of the energy. The Fermi-level pinning model is assumed [23]. The number of the electrons in a QD is not fixed to an integer number and is determined by E F and the potential energy.…”

Quantum Dot Systems: a versatile platform for quantum simulations

“…The second most important are the undesired background (bulk) impurities, which can have a density as low as 1 − 5 × 10 13 cm −3 [119,120], and cause most of the disorder in undoped systems [121]. Surface charges can also induce disorder, and mainly influence shallow (30 − 40 nm deep) 2DEGs.…”