A simple method to evaluate the plasma spreading velocity in high power thyristors

The experimental determination of plasma spreading velocity versus current density in high power thyristors has been performed by many authors in different ways, especially by means of the observation of infrared recombination radiation [1], [2], [3] and the measurement of voltage with electrical probes [1], [4], [5]. In this paper a method is presented which, from the forward dynamic voltage measurement on finished devices, allows, on particular structures, to calculate analytically the experimental constants that appear in the relation between plasma velocity and current density.