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 asVnwherenis 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.