On the Changes in Contact Potential Difference of a Germanium Rectifier During the Electrical Forming

Abstract

It has been found experimentally that the change in contact potential difference Δ V D during the forming process can be determined by observing the variation of a saturation current in the reverse direction with time required for the forming, the values of Δ V D obtained for three kinds of surfaces ranging from 0.16 V. for a etched surface, from 0.06 V. to 0.07 V. for a cleaved surface, and from 0.04 2 V. to 0.04 6 V. for a surface exposed to nascent hydrogen. The theoretical treatments have been investigated to explain the experimental results, using the idea of Bardeen's surface levels and assuming that the variations in concentration of donor impurities present in the barrier, which had been caused by the thermal diffusion of acceptor impurities from the surface of the semiconductor, would affect the contact potential difference. The qualitative predictions appear to agree with results satisfactorily.