Forward and Reverse Tunnel Currents in Gallium Phosphide Diffused p-n Junctions

Abstract

The current‐voltage characteristics of zinc‐diffused and beryllium‐diffused p‐n junctions in gallium phosphide have been studied at temperatures between 77° and 300°K. The dominant forward current over most of the bias range for the zinc‐diffused diodes varied as exp (βV+γT), where β and γ are relatively independent of temperature and voltage. This current was shown to be qualitatively consistent with a simple tunneling model involving states in the forbidden gap. For high bias in the zinc‐diffused diodes and for most of the bias range in the beryllium‐diffused diodes, the dominant forward current was due to thermal recombination in the space‐charge region via deep traps. The reverse current in the pre‐avalanche breakdown region for all diodes appeared to be dominated by internal field emission, or Zener tunneling.