Undoped liquid-encapsulated Czochralski-grown crystals, with a transition from semi-insulating to medium-resistivity behavior, exhibited unusually low values of the Hall mobility at 300K in the transition region. In this region, an anomalous temperature dependence of the mobility was characterized by an increase with increasing temperature at up to 400K. By means of model calculations, using standard effective-medium theory, it was shown that this anomalous behavior was due to the existence of mesoscopic electrical non-uniformities that were connected with the cellular structure of dislocations.

W.Siegel, S.Schulte, C.Reichel, G.Kühnel, J.Monecke: Journal of Applied Physics, 1997, 82[8], 3832-5