The temperature dependence of the contrast which was associated with individual threading dislocations and cross-hatch patterns, from 12 to 300K, was examined by using a near-field scanning optical microscope to carry out local photocurrent measurements. An observed weak contrast at room temperature, and a negative temperature coefficient, indicated that the predominant electrical activity arose from shallow centers. This was consistent with the presence of intrinsic defects or, at most, low levels (order of ppb) of contaminants. The cross-hatch contrast exhibited long-range variations below 100K.

Temperature Dependence of Dislocation Photoresponse in Relaxed GeSi Films M.H.Gray, J.W.P.Hsu: Applied Physics Letters, 2000, 76[10], 1294-6