X-ray-diffraction measurement of interface structure in GaAs/Si(001)

We have developed an x-ray-diffraction technique that provides depth sensitivity to the near-interface region of a thick, nonregistered film. By measuring the intensity profiles along the Si[00l] substrate crystal truncation rods, we compare the diffraction from the Si/GaAs interface with a model based on a grid of misfit dislocations. We find that the interface atoms have a root-mean-square displacement of 1.09±{}0.10 {} and that the interface has a roughness of 2.9±{}1.0 {}. The diffraction indicates an anomalously small strain perpendicular to the interface in the GaAs near the interface.