Surface kinetics and growth interruption in molecular-beam epitaxy of compound semiconductors: A computer simulation study

The dynamics of the growth front smoothness recovery following growth interruption in molecular-beam epitaxy of III-V compounds is examined via Monte Carlo computer simulations. Results are obtained as a function of the substrate temperature and group-V pressure and found to be remarkably similar to the behavior of the reflection high-energy electron diffraction (RHEED) specular beam intensity recovery measured near the first out-of-phase condition. An initial fast smoothness recovery is shown to be a combined effect of rapid interlayer movement of essentially isolated group-III atoms and the continued dissociative adsorption of the group-V molecules. The temperature dependence of the short time constant representing the fast initial recovery of the RHEED specular beam intensity thus does not necessarily provide a measure of the group-III surface diffusion coefficient. Results are also presented for the smoothness recovery behavior of Alx Ga1−x As alloys. The consequences of the differences in Ga and Al kinetic rates for the chemical nature (lateral and in the growth direction) of normal and inverted interfaces formed following growth interruption are discussed. The findings support earlier interpretations of the photoluminescence data on Alx Ga1−x As quantum well structures grown employing growth interruption.