Arsenic Clustering in Silicon

Large decreases in the conductivity of arsenic-doped silicon have been observed during 500–970°C heat treatments. The rate of conductivity change depends upon the prior quenching rate from diffusion temperature to room temperature. These conductivity changes are reversed by higher-temperature treatments. The relationship between the electrically active arsenic, as calculated from the conductivity, and the total arsenic is shown to be consistent with a model of substitutional arsenic atoms being nonionized when in a cluster or in a complex involving one or more vacancies.