Secondary breakdown and degradation in germanium alloyed PN junctions

A failure mechanism is described that accounts for the degradation of the reverse characteristics of germanium alloyed junctions when pulsed in the reverse direction. This mechanism involves both surface breakdown and secondary breakdown. Visible avalanche breakdown emission has been observed at localized spots onreverse biased N⁺P junctions. Failure during pulsing always occurs at one of these spots. This observation together with the results of other experiments have shown that surface treatments commonly used during manufacturing leave the surface of NPN transistors with anti-channeling surface breakdown sites, This is not true, in general, for PNP alloy transistors.