The cathodoluminescence contrast of curvilinear dislocations that were oriented parallel to the surface, and were identified as being  and  dislocations, were observed at some depth below the indented basal surfaces of the sulfide. A correlation between the dislocation structure under the contact, and the shape of the deep-level spectrum, was detected by means of deep-level transient spectroscopy. It was shown that only  dislocations were associated with the appearance of an additional level in the top half of the band gap. Indentation of the basal surface, and subsequent etching of the surface layer close to the penetration depth of the indenter, could be used to investigate separately the properties of  and  dislocations in crystals with the wurtzite structure.

O.F.Vyvenko, A.A.Istratov: Fizika Tverdogo Tela, 1995, 37[2], 516-24 (Physics of the Solid State, 1995, 37[2], 279-83)