Structural properties of GaAs on (001) oriented Si and Ge substrates

Abstract

A detailed x-ray scattering study of GaAs grown by molecular beam epitaxy on (001) oriented Si and Ge substrates is reported. It is shown that the broadening of the GaAs Bragg peaks can be understood in terms of residual strains for samples 2 μm thick. For a sample 0.2 μm thick, domain size broadening effects corresponding to the total thickness of the GaAs film must also be included in order to explain the peak widths. In none of the samples was any evidence of antiphase domain broadening observed and we are thus able to place a minimum of 4000 Å on the size of any possible antiphase domains. We also find that the GaAs lattice is incommensurate with the Si substrate and that the GaAs is tetragonally distorted at room temperature. This distortion is explained by the difference in the thermal expansion of GaAs and Si.