Polar state of a particle with a degenerate band spectrum in a quantum dot

The energies of electron and hole polarons in spherical quantum dots based on materials with a high degree of ionicity are found. It is established that consideration of the valence-band degeneracy causes the hole polaron binding energy to be greater than the electron polaron binding energy. The polaron effects increase with decreasing quantum dot radius. Interband optical transitions are accompanied by partial compensation of the polaron effects, because the emergent electron and hole tend to create polarization potential wells with opposite signs. It is shown that complete compensation of the polaron effects does not occur when the valence-band degeneracy is taken into account. Therefore, interband transitions are accompanied by polarization of the medium. Such polarization is manifested by the appearance of a series of intense phonon replicas of the lines for the electronic transitions. (C) 1999 American Institute of Physics. [S1063-7826(99)01507-0].