Lowering the Breakdown Voltage of Silicon <i>p-n</i> Junctions by Stress

Abstract

A reversible reduction of breakdown voltage is observed when mechanical stress is applied to silicon p-n junctions. This effect can best be investigated in junctions exhibiting uniform avalanche breakdown. When uniaxial stress is applied the normalized reduction of breakdown voltage ΔV/VB is proportional to stress, the proportionality constant being of the order of 10−12 dyn−1 cm2. When stress is applied by means of a flat stylus, ΔV/VB is proportional to the load, when a spherical stylus is used, ΔV/VB is proportional to the cube root of load. It can be shown that the relative current change for a given force is to a first approximation independent of diode area and breakdown voltage VB. It is proposed that the effect is caused by reduction of the energy gap.