The cathodoluminescence contrast of curvilinear dislocations which were oriented parallel to the surface was attributed to the presence of α and β dislocations which were located at some depth below indented basal surfaces. A correlation between the dislocation structure below the contact point, and the shape of the deep-level spectrum, was demonstrated by means of deep-level transient spectroscopy. It was shown that only β dislocations were associated with the appearance of an additional level in the upper half of the band-gap. It was found that indentation of the basal surface, and etching of the surface layer close to the penetration depth of the indenter, could be used to investigate independently the properties of α and β 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)