Magneto-optics of acceptor-doped GaAs/Ga1−xAl

Abstract

The effect of carrier density, magnetic field, and final-state interactions on the radiative recombination of electrons with holes localized on acceptors in GaAs/Ga& "Al"As heterostructure is investigated. In the high-density regime, strong oscillations of the position and intensity of the emission spectrum as a function of the magnetic field are observed at even filling factors. In the low-density regime, an almost perfect cancellation of many-body effects in emission from the first subband is observed accompanied by oscillations of the emission intensity of the second subband magnetoexcitons. The peaks in the intensity of the second subband emission occur at the integer values of the ratio of the subband separation to the cyclotron energy. These results are explained by the calculated self-consistent subband structure and emission spectrum including shake-up and excitonic effects.

Role of Hole Localization in the Magneto-Luminescence of a Two-Dimensional Electron Gas

“…Optical measurements on the high mobility two-dimensional electron system (2DES) have been performed over a long period [1][2][3][4][5][6][7][8][9][10][11][12][13] to study electron interactions through their effect on the optical emission properties. Many-body effects (329) have an influence on the optical spectra, as revealed by the appearance of charged excitons at low electron densities [11], shake-up processes [12], and optical singularities at the Fermi level (FES) [13].…”

“…This is often the main drawback of optical methods compared to transport measurements. One way to minimize this perturbation is to use a modulation-doped semiconductor heterojunction (HJ) [1][2][3][4][5][6][7][8], instead of a quantum well (QW) [9,10] where the electrons and holes are close to each other. In HJs the photocreated holes tend to escape away from the interface due to the built-in electric field.…”

“…This can be achieved either by trapping at uncontrolled interface defects, by screening of the electric field (band flattening) due to residual doping [1] or by trapping of the photocreated hole (PCH) at a δ-layer of acceptors (normally Be) located at a certain distance from the HJ [2][3][4][5]8]. This last method has been widely used to investigate the 2DES in the integer [3,8] and fractional [2,4] quantum Hall regimes. A large variety of magneto-photoluminescence (MPL) characteristics of the 2DES have been reported in the past, which depend strongly on the sample structure and details.…”

Photoluminescence measurements in Be-δ-doped back-gated quantum well

“…We focus on the PL from the recombination of the electrons with a hole bound to the negatively charged acceptor. The advantage of this method is that the optical selection rule in the recombination is relaxed due to the strong localization of a hole at the acceptor site and the PL spectrum provides a direct method for investigating the energy spectra of electrons in 2DES [6,7,8].The layer structure of the sample is shown in the inset of Fig.1. The layers consist of a Si-doped GaAs substrate, overgrown by molecular beam epitaxy with a 1000 nm heavily-Si-doped GaAs layer, which acts as a back gate, followed by a barrier layer comrising 150 periods of GaAs(2-nm thick)/AlAs(2-nm thick) superlattice and 20 nm of Al 0.3 Ga 0.7 As.…”

“…We focus on the PL from the recombination of the electrons with a hole bound to the negatively charged acceptor. The advantage of this method is that the optical selection rule in the recombination is relaxed due to the strong localization of a hole at the acceptor site and the PL spectrum provides a direct method for investigating the energy spectra of electrons in 2DES [6,7,8].…”