Francisco A. P. Osório

Electron-phonon effects on the ground impurity level in quasi-one-dimensional semiconductor heterostructures

Abstract We calculate the effects of the electron-phonon interaction on the binding energies of an impurity placed in a quantum-well wire of rectangular cross section and finite barrier potential to the confined electrons. The calculations are performed as a function of the size of the wire for different positions of the impurity and for several values of the heights of the barrier potential. The results show that the energies are almost the same in wires with comparable cross-sectional area.

Cyclotron resonance of electrons in GaAsGa1−xAlxAs heterojunctions

Abstract The cyclotron resonance mass of a quasi-two-dimensional polaron in GaAsGaA1As heterostructures and quantum wells is calculated. Experimental results recently obtained by different groups are well described in the magnetic quantum limit.

SHORT-RANGE CORRELATION EFFECTS IN A POLARON GAS IN GaAs AlGaAs QUANTUM WELL WIRES

We investigate the short-range correlation effects of plasmon–phonon collective excitations in a quantum well wire by using the self-consistent field approximation theory proposed by Singwi, Tosi, Land and Sjolander [Phys. Rev.176, 589 (1968)]. In our calculation model, we consider a three-subband model with only one populated, for a rectangular cross-section quantum well wire with infinite height for the potential barrier. We have verified that by decreasing the wire width (and/or decreasing the electronic density), the local field correction effects are increased. We compare the present results with those obtained within the Random Phase Approximation throughout the paper and found that the differences between the two calculation methods are more significant for the intrasubband plasmon.

Polaronic effects on the collective excitation in a GaAs parabolic quantum wire

In this paper, the plasmon-longitudinal optical (LO) phonon interaction effects on the intrasubband structure factor, on the pair correlation function and on the intrasubband plasmon energy associated with the lowest subband in a GaAs parabolic quantum well wire (QWW) are investigated by varying the subband separation energy and the electronic density. The calculations are performed using the self-consistent field approximation, which includes the local-field correction within the Singwi, Tosi, Land and Sjolander (STLS) theory, at zero temperature and assuming a three-subband model where only the first subband is occupied by electrons. The theoretical results obtained via STLS theory are compared with the random phase approximation (RPA) approach results, in order to emphasize the importance of the local field corrections (LFC) for the calculation of the collective excitations in quasi-one-dimensional systems.

Inter-subband structure factor for a quasi-one-dimensional polaron gas

In this work, the collective excitation spectra of quasi-one-dimensional plasmon in a rectangular GaAs quantum wire is investigated. Our calculations are performed within the Singwi, Tosi, Land and Sjolander (STLS) self-consistent theory taking into account the plasmon–longitudinal optical (LO) phonon coupling effects. We have employed a three subband model with only the first subband occupied by electrons and we have considered intra-subband and inter-subband transitions. We show that the polaronic effects cause the appearance of dips and oscillations in the static structure factor dispersion relation, which are directly related with the oscillator strength transfer between the collective excitation energy branches. We have also observed oscillations in the pair-correlation function that are characteristic of inter-subband transitions and it denotes partial localization of the particle.

Visible light generation in semiconductor nano-pillars

We report a calculation of the two first energy levels of semiconductor nano-pillars as a function of their diameters. We have considered GaAs and InAs self-assembled quantum dots disk-like shape. The region where the visible light is emitted was delimited. Encapsulating quantum dots with diameters from this region allows the fabrication of white light-emitting diodes.