Metal Precipitates in Silicon <i>p-n</i> Junctions

Abstract

Metal precipitates in junctions were found to cause excess reverse current below avalanche breakdown, which is conjectured to be due to Zener tunneling at localized high-field points. This current varies as Vn where n is between 4 and 7. By a potential plotting method, it was shown that this excess current is not caused by a surface effect. Metal precipitates can be removed or prevented by ``gettering'' from surface layers. Metallic coatings and certain glassy oxide layers were investigated. Results indicate that layers of Ni and Zn have a limited gettering effect. Glassy layers, especially those of boron and phosphorus, have the greatest gettering effect.