Overlapping phenomena and dislocation energy levels in germanium

Abstract

The dependence on dislocation density of Hall coefficient and resistivity was examined at temperatures ranging from liquid nitrogen to 190° K, inn-type germanium. Over the whole temperature range the dependence on dislocation density has two branches, which precede the transition top-type occurring at higher dislocation densities. The results were discussed on the basis of two different models assuming that the dislocations are surrounded either by space-charge cylinders plus low-mobility rings or by space-charge cylinders only. In both cases the experimental data correspond to dislocation energy levels in the upper midgap. Thus the possibility that thep-type characteristics are connected with acceptor levels other than those of the dislocations, but probably with point defect associates was considered. Inhomogereity effects were also taken into account; these can explain the absence of a plateau in the effective donor concentration dependence on temperature as well as the transition top-type.