Instability in Low-Temperature Molecular-Beam Epitaxy Growth of Si/Si(111)

Abstract

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