Dislocation emission in CdS

The dependence of the dislocation emission spectra of CdS crystals on optical excitation intensity, dislocation types, and temperature are investigated. The excitation spectra of dislocation emission at 6 K are studied as well. Considerable differences between the optical spectra due to basal and prismatic dislocations are observed especially in high-resistivity crystals at low excitation intensity. They are attributed to the difference in core structures of these dislocations. The observed peculiarities of the influence of basal dislocations on optical properties of CdS crystals are supposed to be due to an effect of the electric field of a charged dislocation core when this field is weakly screened by a space charge of impurity atoms or free carriers. The scheme of radiative transitions forming the dislocation emission spectrum is proposed. The binding energies of electron and hole trapped due to the deformation potential of dislocations are defined.