Theory of Confined States of Positronium in Spherical and Circular Quantum Dots with Kane's Dispersion Law

Confined states of a positronium (Ps) in the spherical and circular quantum dots (QDs) are theoretically investigated in two size-quantization regimes: strong and weak. Two-band approximation of Kane dispersion law and parabolic dispersion law of charge carriers are considered. It is shown that the electronpositron pair instability is a consequence of dimensionality reduction, not of the size quantization (SQ). The binding energies for the Ps in circular and spherical QDs are calculated. The Ps formation dependence on the QD radius is studied.