Optical-absorption spectra associated with shallow donor impurities in spherical infinite-well GaAs quantum dots

The optical-absorption spectra associated with transitions between the n=1 valence level and the donor-impurity band has been calculated for spherical GaAs quantum dots with infinite potential confinement, using a variational procedure within the effective-mass approximation. We show results either for one impurity and for a homogeneous distribution of impurities inside of the quantum dot. The interaction between the impurities has been neglected. The main features found in the theoretical spectra were an absorption edge associated with transitions involving impurities at the center and a peak related to impurities at the edge of the dot. For all sizes of the quantum dot the peak associated with impurities located next to the edge always governs the total absorption probability. The results are compared with previous results in quantum wells and quantum-well wires of comparable dimensions. (C) 1997 American Institute of Physics.