A Reversed Carrier Transport Effect in Germanium

Abstract

The difference in the behaviour of electrons and holes in germanium in the degree of departure from linearity of their drift velocity-electric field relationships is shown theoretically and experimentally to influence substantially the motion of a density distribution in near intrinsic material at high fields. In n-type germanium the normal motion can be reversed. A consequence is that injection or extraction, depending on the nature of the contact, can occur from the negative end of an n-type specimen. Cross section variations can also act as sources of injection or extraction. An apparent negative resistance has been observed, and a tentative explanation is given. Changes in mobility ratio due to mechanical stress can have an appreciable effect at high fields, and it is shown that even at low fields interpretation of piezoresistance measurements could be influenced by these considerations.