Electrical Effects of Screw Dislocations in Germanium

Extrinsic conductivity on plastically deformed germanium containing predominantly screw dislocation arrays were investigated. The dislocations were introduced by twisting cylinders of anitmony-doped n-type germanium and the dislocation density was determined by the etch pit method. Dark conductivity and both transient and steady-state photoconductivity were measured on Hall-type samples for current flow parallel and perpendicular to the dislocation arrays on the active slip planes. Measurements were made at room and liquid-nitrogen temperatures and the effects of varying the annealing procedure, the temperature of deformation, the amount of twist, and the arrangement of the dislocation arrays are presented. The results indicate that screw dislocations do not have associated acceptor levels in germanium.