SURFACE RECOMBINATION IN GAAS PN JUNCTION DIODE

Surface recombination in GaAs PN junction is investigated. It is argued that the commonly used expression for surface recombination current proposed by Henry et al. represents the current due to injection of carriers from the bulk to the surface from only one site within the junction depletion region where electron and hole densities are equal. This current with an ideality factor of 2 represents drift diffusion of carriers in the surface channel within the junction depletion region. At low forward bias, the neglect of injection from other sites results in little error but at higher forward bias the recombination current resulting from injection outside the junction becomes more important. It is shown that the latter may not always have an ideality factor of 1 as is commonly assumed.