Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 10: Semiconductor Substrates: Epitaxy and Growth

O 10.6: Talk

Monday, February 25, 2008, 14:30–14:45, MA 042

Influence of an Ehrlich-Schwoebel barrier on growth oscillations during epitaxy in layer-by-layer mode — •Christian Heyn — Institut für Angewandte Physik, Universität Hamburg, Germany

We study the mechanisms behind the damping of reflection high-energy electron diffraction (RHEED) oscillations during layer-by-layer growth of GaAs and AlAs. Experimental data are compared to results of both a kinetic Monte Carlo simulation as well as a rate equations based growth model. The rate model considers in particular reversible aggregation and interlayer migration. With the rate model, we find that the height of the Ehrlich-Schwoebel barrier for interlayer migration significantly influences the oscillation damping. Under consideration of an Ehrlich-Schwoebel barrier, the rate model quantitatively reproduces experimental oscillation damping as function of growth temperature and speed. Furthermore, the presence of an Ehrlich-Schwoebel barrier explains the more strongly damped oscillations during GaAs growth in comparison to AlAs. AlAs has a higher energy barrier for surface diffusion but a lower Ehrlich-Schwoebel barrier. From a quantitative analysis we obtain values of the Ehrlich-Schwoebel barrier height for GaAs of 0.134 eV and AlAs of 0.069 eV.