Effect of Mechanical Stress on p‐n Junction Device Characteristics

A theoretical model is developed for the effect of mechanical stress on the electrical characteristics of Ge and Si p‐n junction devices. This model is based upon the stress‐induced variations in energy band structure and their effect on minority carrier densities. The changes in minority carrier densities are shown to depend upon the type of stress applied, with anisotropic stresses causing larger changes than hydrostatic stresses. From the calculated dependence of minority carrier densities upon stress, the equations are developed for the current—voltage characteristics of diodes and transistors under stress.Following the general analysis several examples are given in which stress is applied to a small section of a junction in a diode or transistor. The results show that at stress levels greater than 1010 dyn/cm2, the device currents can change by several orders of magnitude when stress levels are changed by a factor of 2. The theory is compared with published experimental data and found to be in good a...