Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 49: Surface Chemical Reactions and Heterogeneous Catalysis III

O 49.2: Talk

Wednesday, April 2, 2014, 10:45–11:00, PHY C 213

Degree of hydrogenation of the reconstructed Si(001)-surface under MOVPE-conditions - A DFT study — •Phil Rosenow and Ralf Tonner — Philipps-Universität Marburg, Fachbereich Chemie, Hans-Meerwein-Str. 4, 35032 Marburg

In order to model the metal organic vapor phase epitaxy of III/V-semiconductors on the silicon surface for the integration of laser devices in electronic circuits, the properties of the surface under the relevant conditions must be known beforehand. Especially the extent of hydrogenation is important for the reactivity of the surface. A DFT-based thermodynamics study has been performed on the reconstructed Si(001) surface in order to assess the validity of the theoretical approach compared to experimental observations and prepare for further adsorption studies.

The frequently used ab initio-thermodynamics approach which usually neglects surface contributions to thermodynamic quantities is compared to full phonon calculations. It can be shown that ab initio-thermodynamics overestimates the stability of the hydrogenated surface compared to full phonon calculations. The difference between the two can be used as a fitting parameter to obtain an expression for the extent of hydrogenation dependent on any MOVPE-conditions, in accord with experiemental observations and allowing for a consistent computational treatment of the adsorption process on an atomistic scale.