INSTABILITY IN LOW-TEMPERATURE MOLECULAR-BEAM EPITAXY GROWTH OF SI/SI(111)

Using high-resolution low-energy electron diffraction we studied in situ low-temperature molecular-beam epitaxial growth of Si/Si(111). At similar to 275 degrees C and a deposition rate of similar to 7 bilayers/min, a roughening evolution occurs after an initial transient layer-by-layer growth. It shows dynamic scaling characteristics with a roughness exponent a approximate to I and an interface growth exponent beta = 1/4. More importantly, the average local slope is found to increase with time as similar to root 1n(t). However, such a roughening behavior does not exist either at temperatures higher than 350 degrees C or under a slower deposition rate of similar to 1 bilayer/min. The phenomena are consistent with a statistical model of linear diffusion dynamics.