Electronic structure and impurity states in GaN quantum dots

We study the electronic structure of spherical GaN quantum dots (QD's) with a substitutional acceptor impurity at the center. The size-dependent energy spectra are calculated within the sp³s* tight-binding model, which yields a good agreement with the confinement-induced blue shifts observed in undoped QD's. The acceptor binding energy is strongly enhanced in a QD and decreases with increasing size following a scaling law that extrapolates to the bulk experimental value. The size-dependent average radius of the hole orbit is also calculated. The results are in agreement with the available experimental data for Mg impurity in bulk GaN.