Storage time variations in silicon p+-n-n+diodes

Using the reverse-recovery technique, storage times have been measured as a function of forward current density for p⁺-n-n⁺diodes of different diameters. There exists an upper limit to the storage time at high injection levels, independent of diode diameter. Analysis shows that as the forward current density, and hence, the average injected charge density, is increased, the bulk lifetime decreases and the recombination velocity at the n-n⁺interface increases. The recombination velocity at the n-layer sidewalls is effectively infinite in all cases. With these results the computed forward resistance as a function of injection level of a p⁺-n-n⁺diode agrees reasonably well with the measured values.