Spectra of acceptors in quantum dots: the effect of a magnetic field

We report calculations of the energy spectra of shallow-acceptor impurities in GaAs/Ga1-xAlxAs quantum dots in the presence of external magnetic fields. We calculate the binding energies of the ground and excited acceptor states in the effective-mass approximation using a formalism based on a four-band model that includes the coupling of the spin to the magnetic field as well as the valence-band mixing, The potential of the acceptor is taken to be the screened Coulomb potential of a point charge, and we take into account the mismatch of the dielectric constant through the method of image charges. We present a complete analysis of the acceptor binding energies as a function of the lateral confinement of the quantum dot and as a function of the magnetic field strength. We also discuss the role of the mixing of heavy holes and light holes in determining the acceptor spectrum in the different regimes of confinement.