Simultaneous effects of temperature, pressure, polaronic mass, and conduction band non-parabolicity on a single dopant in conical GaAs-Al x Ga1–x As quantum dots

Abstract

This paper is devoted to the theoretical study of the simultaneous effects of temperature, hydrostatic pressure, conduction band non-parabolicity, and polaronic mass on the electronic states and the photoionization cross-section of a shallow donor impurity confined in a GaAs-Al x GaAs conical quantum dot. The calculations have been made within the effective mass approximation. The shallow donor impurity energy levels have been calculated by employing two methods: the variational approach and the finite element method with finite and infinite confining potential. The obtained results suggest that the effects of conduction band non-parabolicity, temperature, hydrostatic pressure, and variation of the conical quantum dot geometries play a significant role in determining of the electronic states system, as well as in the photoionization cross-section. It is also shown that the donor binding energy is very sensitive to temperature and hydrostatic pressure. Indeed, the temperature decreases the donor binding energy while it is increasing with the applied hydrostatic pressure. Also, the quantum dot effective gap is severely affected by the conduction band non-parabolicity. In the case of polaronic mass effects, the present study suggests that they can be omitted without significantly affecting the study’s main conclusions. In this paper, structures with an apical angle ranging from 10° to 150° are approached, allowing simulating quantum dots with a radius of the base much greater than the height and structures with a height much greater than the radius of the base. In the case of hydrostatic pressure and for quantum dots with finite confinement potential, the Γ-X crossover effect has been considered, which is responsible for significant changes in the carriers’ confinement potential.