Linear dichroism in optical spectra of Co-ions in CdS

Absorption spectra of hexagonal CdS doped with Co were studied. The investigations were carried out in the spectral range from 1.42 to 1.98 eV with linear polarized light E||c, E⊥c (c is the optical axis of CdS) propagated in the direction (1-2 1 0). The spectra were measured using static and λ-modulation (with Lock-in technique) method. It has been proved the Co-ions influence on the spectral position of the absorption edge and the Urbach's constant. Co-ions cause a considerable change of the optical spectra in the transparence region where an impurity structure appears. This structure manifests linear dichroism in the case of wave vector k||(1-2 1 0). The linear dichroism is not established for k||(0 0 0 1). The peculiarities of the linear dichroism spectra of Co-ions in CdS were analyzed and discussed.