The potential and carrier distributions of a p-n-p-n device in the ON state

The potential and carrier distributions of a p-n-p-n device in the ON state are measured by electrical and optical probing techniques. The measurements are compared with numerical calculations of the potential and carrier distributions and the current-voltage characteristics as a function of device temperature. The calculations are based upon an analysis of the p-n-p-n device at high current densities using an abrupt junction model and including the effects of carrier-carrier scattering, conductivity modulation, and the dependence of emitter efficiency upon current density. The conditions under which the p-n-p-n device may be approximated by a p-n-n
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device are also considered. The range of applicability of the results includes all ON currents of practical interest in a p-n-p-n device.