Confinement Dependence of Bound Polaronic Energies in Anisotropic Quantum Dots under Magnetic Fields

Energy levels of a polaron bound to hydrogenic impurities in anisotropic double-parabolic quantum dots are investigated by the second order perturbation theory. The polaronic energy corrections are expressed as a function of the confinement strength in different directions and the magnetic field applied along the growth direction. With characteristic parameters pertaining to GaAs, it is found that as the effective thickness reduces, the energy correction to higher subbands increases at a much larger rate than that to the lower subband. The polaron binding energy for higher subbands may become larger than that for the lower subband in the case of sufficiently thin quantum dots, in contrast to the normal energy level structure.