The binding energies of shallow donor impurities in GaAs quantum-well wires under applied electric fields

Abstract

Using a variational procedure, within the effective mass-approximation, we calculate the binding energy of a shallow-donor impurity in a rectangular cross-sectional area of a GaAs quantum-well wire, under the action of an electric field applied perpendicular to one of the interfaces, assuming an infinite-confinement potential. We study the binding energy of the donor impurity as a function of the system geometry, the applied electric field, and the donor-impurity position. It was found that the presence of the electric field breaks down the degeneracy of the states for impurities symmetrically positioned within the structure. Our results for a large length of one side of the cross-sectional area coincide quite well with previous results in quantum wells. We show, unambiguously, that the impurity binding energy depends strongly not only on quantum confinement, but also on the applied electric field and on the distribution of impurities inside the quantum-well wires; these aspects must be taken into account in the quantitative understanding of optical phenomena related to shallow impurities when an electric field is applied.

Hydrogenic impurities in graded GaAs–(Ga,Al)As quantum-well wires in an electric field

“…These parameters are suitable in GaAs/Ga 1Àx Al x heterostructures with an Al concentration of xD0:3 [14,30]. We have assumed the conduction-band discontinuity to be 56% of the total band gap difference between GaAs and Ga 1Àx Al x As, and the donor is located at the center of the wire.…”

“…The importance of studying the influence of an electric field on the binding energy, the state density, the polarizability have theoretical as well as technological relevance. The effect of an electric field, and the geometric form of the system on the binding energies of shallow-donor impurities in GaAs quantum-well wires was presented by several authors [14][15][16], considering an infinite confinement potential and using a variational scheme. Duque et al investigated the effect of an applied electric field on the binding energy, and polarizabilities of shallow-donor impurities implanted in rectangular cross-section GaAs-GaAlAs quantum-well wires [17], and in cylindrical GaAs low-dimensional systems [18].…”

Impurity‐related optical properties in rectangular‐transverse section GaAs–Ga1–xAlxAs quantum well wires: Hydrostatic pressure and electric field effects

“…Some studies have been reported on the applied electric field and hydrostatic pressure dependencies of the shallow-donor-impurity and/or acceptor-impurity binding energies of the ground and first few excited states in QWW heterostructures [1][2][3][4]. The aim of the work reported in the present paper was to study the hydrostatic pressure and electric field effects on confined donor and acceptor impurities in transverse-rectangular section GaAs-(Ga,Al)As QWWs.…”

Electric field effect on the binding energy of a non‐hydrogenic donor impurity in a cylindrical cross‐sectional quantum well wire

“…The influence of an electric field on the hydrogenic binding energy was presented by several authors [25][26][27][28][29][30][31][32]. The effect of an electric field and the geometric form of the system on the binding energies of shallow donor impurities in QWWs was presented by Montes et al [25,28] and Ulaş et al [26,27]. They found that the hydrogenic binding energy of a shallow donor impurity is a rather sensitive function of the geometry of the QWW and of the distribution of impurities inside the QWW.…”