Resistance of Elastically Deformed Shallow p-n Junctions. II

Abstract

An effect of large anisotropic stresses to lower the resistance of shallow p-n junctions reversibly by several orders of magnitude has been extensively investigated. Even though large stresses have been used it was found that their anisotropies were of greater significance than their magnitudes. The effect was found to increase strongly with decreasing junction depth. Of the crystal planes studied in Ge, the effect was largest with junctions lying in the (111) planes and smallest with junctions in the (100) planes. In both Ge and Si the effect increased with increasing temperatures. Stress-frequency response was observed from dc to 100 kc. The same effect in transitors caused reversible changes in collector current by factors up to nearly 1000 for a constant emitter current. Stress and strain analyses indicated large energy-gap changes with pronounced extrema. At the present stage, none of the known stress effects on the resistance of homogeneous semiconductors or junctions could be satisfactorily correlated with the magnitude and the various manifestations of the present stress effect. A tentative model is considered, based on a stress controlled generation-recombination rate of carriers due to generation and elastic distortion of dislocations.