Current–voltage characteristics of power diode structures with strong asymmetry of emitters injection ability

In the paper, diode structures with strong asymmetry of emitter injection ability have been investigated. In these structures the base width was approximately equal to the ambipolar diffusion length. It was shown that at a high current density for correct description of charge carrier transport in these structures in addition to commonly used diffusion and quasyneutral drift regimes it is necessary to take into account a recently discovered regime DSQD (diffusion stimulated by quasineutral drift). It is shown that at high current densities the width of the region where quasineutral drift regime is realized tends to become smaller. Due to this effect in these structures the current–voltage characteristic may become of $S$-type even at comparably small values of the ratio $W/L$ ($W$ – is the base layer width, $L$ – is the ambipolar diffusion length).