Uniform Silicon <i>p-n</i> Junctions. I. Broad Area Breakdown

TLDR

It is believed that the space‑charge regions of these junctions more closely resemble plane‑parallel geometries than any studied similarly hitherto. A comparison is made between the uniform junctions and one that is similar except that it possesses two breakdown‑inducing sites, probably dislocations. Uniform silicon p‑n junctions fabricated without exposed edges or dislocations exhibit avalanche breakdown at roughly twice the voltage of dislocation‑rich junctions, show no intermediate microplasma formation, emit diffuse macroplasma light, and demonstrate that microplasmas are not required for breakdown but arise only with field or lattice inhomogeneities.

Abstract

Small area silicon p-n junctions have been made which are free from exposed edges and dislocations passing through the space-charge region. It is believed that the space-charge regions of these junctions more closely resemble plane parallel geometries than any studied similarly hitherto. The avalanche breakdown phenomena in these uniform junctions are shown to be drastically different from those occuring in junctions that contain many dislocations. A comparison is made between the uniform junctions and one that is similar except that it possesses two breakdown-inducing sites, probably dislocations. In the latter junction the reverse characteristic shows two slightly separated rapid increases in current which coincide, biaswise, with the formation of two isolated light-emitting microplasmas, the occurrence of characteristic microplasma noise, and two singularities in the charge-multiplication characteristics. The uniform junctions show no such phenomena at intermediate voltages, breakdown occurring at a voltage roughly twice that at which the microplasmas form and which was previously thought typical for the given material resistivity. The light emission pattern accompanying breakdown in the uniform junctions appears more diffuse (giving rise to the term—macroplasma) than in nonuniform junctions where it normally appears as an array of intense local spots (microplasmas). It is concluded that microplasmas are not a necessary accompaniment of avalanche breakdown in silicon, but that they tend to occur where there are field or lattice inhomogeneities.