PERIODIC CHANGES IN THE STRUCTURE OF A SURFACE GROWING UNDER MBE CONDITIONS AND RHEED OSCILLATION

The periodic change of the structure and the flatness of a growing surface under MBE conditions are theoretically investigated. The growth of the (001) face of the simple cubic lattice is simulated by using Gilmer and Bennema's model for vapor growth. We discuss the properties of the RHEED oscillation by combining this simulation and a kinematical formula for RHEED intensity. In MBE growth, the lifetime tau-s of an adatom before re-evaporation is much larger than the lifetime tau-c of an adatom before capture by another adatom. If J is the incident beam flux and D(s) is the surface diffusion coefficient of adatoms, tau-c = (JD(s))-1/2. The results of the Monte Carlo simulation and the RHEED intensities calculated for the simulated growth are interpreted in terms of the lifetime tau-c and the mean diffusion length lambda-c in tau-c. We obtain a diagram predicting the growth conditions under which the periodic change of a growing surface causing RHEED oscillation occurs.