Time-resolved X-ray diffraction study on surface structure and morphology during molecular beam epitaxy growth

Summary form only given. Reflection high energy electron diffraction (RHEED) oscillation has been widely adopted for studies on growth kinetics and dynamics in molecular beam epitaxy (MBE). Recent developments in brilliant X-ray sources has enabled similar experiments with X-rays, which has great advantage in a straightforward interpretation of results and in a high angular resolution. In general, the diffracted intensity from surface is proportional to the surface structure factor associated with the surface reconstruction, F, multiplied by a damping factor associated with the surface roughness, m. We show that the two factors, F and m, can be obtained separately by measuring diffuse scattering around the two-dimensional Bragg peak during growth. The experiments were performed with a six-axis surface diffractometer coupled to an MBE chamber at the synchrotron radiation facility, SPring-8. This apparatus allows the sample to be subjected to X-ray measurements at the same position as prepared. The diffracted intensity of X-rays was measured during the homoepitaxial growth of GaAs[001] at a substrate temperature of 700 K. Under the condition used, the RHEED pattern changed from the c(4x4) to the 2x1 symmetry on starting the growth.