Luis C. O. Dacal

Effects of an electron gas on the negative trion in semiconductor quantum wells

Abstract We present here the results of calculations of the negative trion binding energy in the presence of an electron gas. The screening of the Coulomb interaction and the Pauli exclusion principle are considered. Our results show a rapid ionization of the negative trion due to the Pauli exclusion principle while the screening is mainly responsible for the weakening of the trion binding energy.

Effects of effective mass discontinuity on the conductance of three-dimensional quantum wires

We calculate the conductance of three-dimensional semiconductor quantum wires considering different effective masses in the contacts and in the channel. We show that, with respect to the case with equal masses in the channel and in the contacts, the amplitude of the conductance oscillations increases if the electron effective mass in the channel is larger and decreases if it is smaller than in the contacts. Effects on the density of probability are also shown. These effects of the effective mass discontinuity are explained in terms of kinetic confinement and transmission coefficient modulation.

Negatively charged donors in semiconductor quantum wells in the presence of longitudinal magnetic and electric fields

We present variational calculations of the binding energy for negatively charged donors in GaAs/Al0.3Ga0.7As quantum wells. We show that the electronic quantum well ground state and parabolic energy dispersions are enough to obtain accurate results compared with previous Monte Carlo calculations. The configuration interaction method is used with a physically meaningful basis set. We study the charged donor binding energy dependence on the quantum well width and donor position in the presence of external electric and magnetic fields.

Binding Energy of Negatively Charged Exciton in a Semiconductor Quantum Well: The Role of Interface Defects

We present a model to take into account the interface defects contribution on the binding energy of charged exciton in GaAs/Al 0.3 Ga 0.7 As quantum wells. The dependence of the binding energy gain and of the trion size on the quantum well width are variationally calculated. We show that the trion is more sensitive to interface defects than the exciton.

Conductance of three-dimensional cross junctions in the quantum ballistic regime

The influence of dimensionality on the conductance of semiconductor cross junctions is investigated in the effective mass approximation and quantum ballistic regime. Our calculations exhibit some similar features for both two- and three-dimensional models, namely the conductance peaks before the fundamental eigenenergy of the quantum wire that represents the sidearms and the zero conductance dip. Despite this, we show that, in general, the conductance and the electronic wave function are strongly affected when the third spatial dimension is taken into account. In other words, we prove that two-dimensional models are not suitable for representing this kind of system.

Negative Trion Binding Energy in Semiconductor Quantum Wells: Effects of Structural Confinement and Longitudinal Electric Field

We present variational calculations of the binding energy for negatively charged excitons in idealized GaAs/Al 0.3 Ga 0.7 As quantum wells using a physically clear basis set. The presence of a longitudinal electric field is considered and we show the importance of including more than one electron quantum well solution in the basis.