X-ray Diffraction Study of Crystal Growth Dynamics during Molecular-Beam Epitaxy of III--V Semiconductors

An experimental approach to crystal growth dynamics using surface-sensitive X-ray diffraction techniques is discussed. In crystal growth, two essentially different kinds of dynamics are involved. One is the evolution of a statistical structure averaged over the sample area under consideration. The other is the temporal fluctuation of local structures associated with elemental processes of crystal growth, such as the adsorption, desorption, and diffusion of adatoms. Over the past few decades, combination of a synchrotron X-ray beamlines and specially designed crystal growth systems has played a great role in in situ studies of the dynamics of average structures during the epitaxial growth of crystalline films. The recent development of coherent X-ray sources has provided an opportunity to elucidate local structure fluctuation, which is also important for solving many technological ploblems in crystal growth including the control of the uniformity of self-assembled nanostructures and the suppression of defects.