Sticking coefficient reactive

Using a steady-state analysis of the reaction mechanism above, obtain an analytical expression for the TMGa(g) reactive sticking coefficient as a function of so, k, F, and T. 

The surface reactions are based on sticking coefficients. Silylene (S1H2), which is very reactive, has a sticking coefficient of unity. The silane, which is much less reactive, has an activated sticking coefficient, given as... 

Later the barrier puzzle was resolved in a close collaboration between experiment and electronic structure calculations. It turned out that it is not sufficient to just consider the H2 dissociation on clean Si(l 0 0). Instead it was realized that it is very important to take into account the exact surface structure and surface coverage in the determination of the adsorption/desorption barriers [64, 72]. At surface imperfections such as steps the reactivity of a surface can be extremely modified. It was found experimentally on vicinal Si(l 0 0) surfaces that the sticking coefficient at steps is up to six orders of magnitude higher than on the flat terraces [71]. This finding was supported by DFT studies which showed that non-activated dissociation of H2 on the so-called rebonded DB steps on Si(l 0 0) is possible [71, 78], while on the flat Si(l 0 0) terraces the dissociative adsorption is hindered by a barrier of 0.4 eV [37],... 

With respect to deposition processes the most important of the mentioned quantities is the sticking coefficient s. However, its determination requires a rather high experimental effort. An experiment to measure s of selected species will be described in the next section. To get easier access to a figure of merit for the overall reactivity of a radical with surfaces often the surface loss probability... 

An elegant yet technically simple method to determine surface loss probabilities is the cavity technique [30,36-38] A cavity with a small entrance slit (see Fig. 11.2) or a different well-defined geometry - [39-41] is exposed to a flux of reactive species. The transport of the particles is studied via the cross-sectional film thickness profiles. The dimensions of the geometry are chosen much smaller than the mean free path of the neutral radical species so that gas phase collisions are negligible. Then the normalized profiles depend on the surface loss probability (3 only. If the total fluence of particles into the slit is not known no conclusions can be drawn concerning the sticking coefficient except s < / . 

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