Correlated electron-hole transitions in bulk GaAs and GaAs-(Ga,Al)As quantum wells: effects of applied electric and in-plane magnetic fields

Abstract

The effects of crossed electric and magnetic fields on the electronic and exciton properties in semiconductor heterostructures have been investigated within the effective-mass and parabolic band approximations for both bulk GaAs and GaAs-Ga 1−x Al x As quantum wells. The combined effects on the heterostructure properties of the applied crossed electric/magnetic fields together with the direct coupling between the exciton center of mass and internal exciton motions may be dealt with via a simple parameter representing the distance between the electron and hole magnetic parabolas. Calculations lead to the expected behavior for the exciton dispersion in a wide range of the crossed electric/magnetic fields, and present theoretical results are found in good agreement with available experimental measurements.Keywords: Quantum well; Magnetic field; Electric field; Exciton transitions A detailed knowledge of the optical properties of semiconductor heterostructures is of paramount importance for possible device applications. In that respect, the study of exciton properties in those systems is of great interest as such coupled electron-hole (e − h) excitations, which arise from the e−h Coulomb interaction, may considerably modify the interband optoelectronic properties of semiconductor heterostrutures. When the electron and hole carriers are confined in the same region of the direct space and in the same point of the inverse k-space, the exciton is called a direct exciton; alternatively, if the carriers are confined in different regions of the direct space and/or in different points of the inverse k-space the exciton is termed as an indirect exciton. Work on exciton properties have been recently performed both experimentally [1-4] and theoretically [5][6][7][8][9][10][11][12]. Luminescence measurements in GaAs-Ga 1−x Al x As double quantum wells (QWs) under inplane magnetic fields [1,2] have concluded that the dominating radiative recombination of localized indirect excitons does not allow one to observe the quenching of the spatially indirect exciton luminescence and the quadratic shift of their energy under in-plane magnetic fields, with the consequence that the possibility of an exciton dispersion engineering would then be limited in these kinds of samples.Combined theoretical and experimental studies from Ashkinadze et al [11] for the effect of an in-plane magnetic field on the photoluminescence (PL) spectrum of modulation-doped heterostructures have suggested that there are remarkable spectral modifications of the PL spectra in both modulationdoped QWs and high-quality heterojunctions, due to Binduced modifications in the direct optical transitions in QWs, and effects on the free holes in heterojunctions, respectively. Also, studies [12] on the magnetic-field effects on indirect excitons in coupled GaAs-(Ga,Al)As QWs reveal that the exciton effective mass is enhanced as the growth-direction magnetic field increases and, at high fields, it becomes larger than the sum of the e and h masses, suggesting that a magnetoexc...

Excitons in a cylindrical GaAs Pöschl–Teller quantum dot

“…The exciton radiation lifetime is inversely proportional to the overlap integral ($|\int_{{\rm volume}} {} {\Psi} (0,{\rho} ,{\rho} ,z,z)d{\tau} |^{2} $ ) 23–27 which is depicted in Figs. 6(b) and (d).…”

Magneto-Stark effect on exciton in parabolic bandGaAs/〖Ga〗_(0.7) 〖Al〗_(0.3) As quantum well heterostructure

“…External electric and magnetic fields reduces the symmetry of the system, therefore leading to level structures possessing numerous complex splitting of excitonic absorption lines. The analysis of excitonic absorption spectra in both electric and magnetic field strengths has been a long-standing subject from the theoretical as well as experimental point of view (Duque CA et al, 2006). Due to specific material parameters, excitonic properties such as Bohr radius and electric/magnetic field strength units provide the possibility to access exotic regimes more easily compared to standard atomic systems.…”

“…A detailed knowledge of the optical properties of semiconductor heterostructures is of paramount importance for possible device applications. In that respect, the study of exciton properties in those systems is of great interest as such coupled electron-hole (e -h) excitations, which arise from the e-h. Coulomb interaction, may considerably modify the interband optoelectronic properties of semiconductor heterostrutures (Duque et al, 2006). The development of semiconductor nanostructures, such as quantum boxes and dots, by the use of different techniques, has attracted much theoretical and experimental attention (Petroff et al, 1987).…”

“…Optical experimental studies usually would not give much information about the finite center-of-mass momentum of exciton states. Studies in exciton dispersion and related properties have been recently performed both experimentally, through photoluminescence PL and magneto absorption experiments, (Whittaker et al, 1991;Fritze et al, 1996;Butov et al, 2000; measurement of the Fano line shape for resonant states (Oberli et al, 1994) the exciton-mass dependence of the recombination time experimental data on polariton effects, (Houdré et al, 1994;Tredicucci et al, 1995) and recent PL measurements (Ashkinadze et al, 2005) of modulation-doped GaAs/AlGaAs QWs and heterojunctions, as well as theoretically (Gorkov and Dzyaloshinskii, 1967;Paquet et al, 1985;Duque CA et al, 2006).…”