INVERSION OF A DONOR IMPURITY LEVELS IN A SPHERICAL GaAs/Ga_(0.3)Al_(0.7)As/Ga_(0.55)Al_(0.45)As DOUBLE-STEP QUANTUM DOT

摘要

Donor energy levels inversion in a double-step a quantum dot with a small rectangular potential inside a large rectangular potential is analyzed. It is considered a model of a spherical OaAs/Ga_(0.7)Al_(0.3)As/Ga_(0.55)Al_(0.45)As quantum dot in which the electron effective mass and the dielectric constant depend on the Al concentration. In order to solve the Schoedinger equation for a D~0 impurity centered in a QD with spherical symmetry we have used an exact numerical procedure based on trigonometric sweep method. Our results show a considerable enhancement of the binding energy values comparing to previous results due to material parameters dependence. We have found that the curves for the binding energies plotted as functions of the QD radius have a different number of the pronounced peaks, crossovers and inversions of level ordering.