N-S transition in nonisothermal characteristics of silicon diodes and thyristors.

The results of numerical modeling of the stationary nonisothermal current-voltage ( I-U) characteristics of forward-biased high-voltage diodes and thyristors in the interval of current densities J ∼ 200–500 A/cm2 revealed an N-S transition in the shape of these curves and a hysteresis in the constant current source regimes. It is established that the mechanism of these phenomena is related to a temperature-induced decrease in the coefficient of ambipolar diffusion under the conditions of enhanced recombination. Devices with such I-U characteristics can be irreversibly switched by short current pulses from stable states on the working branch to the states with high heat evolution, which leads to a risk of thermal breakdown. [ABSTRACT FROM AUTHOR]