Reduction Mechanism of Threading Dislocation Density in GaAs Epilayer Grown on Si Substrate by High-Temperature Annealing

Abstract

The effects of high-temperature annealing were investigated by transmission electron microscopy (TEM) and secondary ions mass spectroscopy (SIMS) on reduction of threading dislocation density in GaAs epilayers grown on Si substrates. It was found that the dislocation density in the annealed GaAs epilayers grown on Si was remarkably reduced. This phenomenon could be attributed to an increase in the velocity of dislocation glide motion including climb motion caused by reaction with vacancies at high temperature. In addition, specific long dislocations running parallel to the GaAs–Si hetero-interface were observed. The specific dislocations were distributed around the diffusion front of Si atoms in the GaAs epilayer. These results led to a model for reduction of threading dislocation density by high-temperature annealing.