Some Effects of Mechanical Stress on the Breakdown Voltage of p-n Junctions

Various factors determining stress-induced changes in the breakdown voltage of Ge and Si p-n junctions are discussed. A model is developed which accounts for the multivalley band structure of semiconductors such as Ge and Si. Analytic expressions are developed for the change in breakdown voltage ΔV/VB as a function of a general stress. For Si, a linear decrease in ΔV/VB with increasing stress is predicted. The proportionality factor is of the same order of magnitude as the bandgap dependence on hydrostatic pressure. For Ge, an initial increase in ΔV/VB followed by a decrease at high stress levels is indicated. The model is shown to be consistent with reported experimental data.