J.A. Brum

Energy levels and magneto-electric subbands in some quasi uni-dimensional semiconductor heterostructures

Abstract We report energy level calculations in some quasi one-dimensional GaAsGa(Al)As heterostructures in the quasidecoupled approximation. In this case the side lengths L x , L z are characterized by L x > > L z . Conduction and valence levels are studied. The subband mixing is considered and the valence subband dispersions along the wire-axis direction are calculated. The self-consistent problem of the charge transfer in one-side n-modulation-doped quantum wire is solved. Finally, we study rectangular quantum wires subjected to crossed electric and magnetic fields perpendicular to the wire axis.

Optical studies of GaAs quantum well based field‐effect transistor

The optical response of a GaAs‐Ga(Al)As one‐side‐modulation‐doped quantum well is studied by photoluminescence and excitation spectroscopy at T=2 K. The electronic concentration is controlled in a field‐effect‐transistor‐like structure. 1011 cm−2 electrons are sufficient to wipe out the strong excitonic resonances which dominate the photoluminescence excitation spectrum when the well is depleted of its carriers. While the lowest lying excitation peak coincides with the maximum of the photoluminescence line when the GaAs channel is empty, the two peaks move in opposite directions with increasing carrier concentration due to the inflating Fermi surface and to band‐gap renormalization effects.

Landau levels and magnetoluminescence of n-type GaAsGa(Al)As modulation doped quantum wells

Abstract The low temperature photoluminescence of a high quality n-type one side-modulation-doped quantum well is investigated under a magnetic field parallel to the growth axis and varying up to 10 Teslas. A part of the first valence subband is tested and compared to the results of a calculation of the Landau levels performed using a self-consistent Hartree approximation and the Luttinger Hamiltonian for the valence band.

Oscillator strengths of interband magneto-optical transitions in strained-layer heterostructures

Abstract We show that, as a consequence of the strong mixing of the valence subbands, the evaluation of the oscillator strengths associated with the interband magneto-optical transitions is a prerequisite to the interpretation of magneto-optical data obtained in quantum-well structures. We illustrate this by examining the case of a GaSb/AlSb strained-layer superlattice in which the ground valence state is the first light-hole level. We show that in this sample, most of the observable heavy-hole-related transitions involve the second heavy-hole level, i.e. they correspond to a transition which is forbidden at zero magnetic field.

Optical properties of one-side modulation-doped quantum wells

Abstract The low temperature optical properties of one-side GaAs/Ga(Al) As quantum wells are studied by photoluminescence and excitation spectroscopy. The electronic concentration is controlled in a FET-like structure and quantitative information on the bandgap renormalization is obtained. The role of excited conduction levels, when populated, is emphasized.