Observation of impurity effects on the nucleation of arsenic precipitates in GaAs

Abstract
The precipitation of arsenic in low temperature GaAs uniformly doped with Si and Be has been studied by transmission electron microscopy. Following an in situ anneal at 600 °C, precipitate size and density is found to be strongly dependent on the dopant type. Impurities at the epilayer/substrate interface lead to heterogeneous nucleation of precipitates. Although precipitates were observed to nucleate heterogeneously at threading dislocations, the precipitates predominantly form homogeneously. These results are consistent with the general theory of precipitation in solids.