Electronic and vibronic states of the acceptor–bound-exciton complex (A0,X) in CdS. III. High-density electronic resonant Raman scattering at the (A0,X) complex

A very strong high-density resonant Raman effect in the bound-exciton region of CdS is explained by electronic B→A hole conversion within the ($A^0$,X) configuration. The ($A^0$,$X_B$) states with one hole from the second B valence band analyzed in paper II of this series [J. Gutowski, preceding paper, Phys. Rev. B 31, 3611 (1985)] act as resonance terms for the incoming photon while the ($A^0$,$X_A$) ground state, involving two A valence-band holes and occupied after the conversion process, forms a resonance term for the scattered light. On the one hand, our model developed in the preceding paper for the ($A^0$,X) complex in CdS is able to explain the scattering process excellently. On the other hand, the resonant Raman scattering is a useful tool for analyzing the highly sensitive dependence of the ($A^0$,X) configuration on the excitation parameters. Thus the spatial dimensions of the complex alter with the energy that is available for its creation. Moreover, high-density excitation results in a stimulation of the Raman transitions. Laser activity of the Raman light becomes observable above a certain threshold of the excitation intensity.