Angular distributions of H-induced HD and D2 desorptions from the Si(100) surfaces

Abstract

We measured angular distributions of HD and D2 molecules desorbed via the reactions H+DSi(100)-->HD [abstraction (ABS)] and H+DSi(100)-->D2 [adsorption-induced-desorption (AID)], respectively. It was found that the angular distribution of HD molecules desorbed along ABS is broader than that of D2 molecules desorbed along AID, i.e., the former could be fit with cos(2.0+/-0.2) theta, while the latter with cos(5.0+/-0.5) theta. This difference of the angular distributions between the two reaction paths suggests that their dynamic mechanisms are different. The observed cos2 theta distribution for the ABS reaction was reproduced by the classical trajectory calculations over the London-Eyring-Polanyi-Sato potential-energy surfaces. The simulation suggests that the HD desorption along the ABS path takes place along the direction of Si-D bonds, but the apparent angular distribution is comprised of multiple components reflecting the different orientations of D-occupied Si dimers in the (2 x 1) and (1 x 2) double domain structures.

Comment on “Angular distributions of H-induced HD and D2 desorptions from the Si(100) surfaces” [J. Chem. Phys. 124, 054715 (2006)]

“…Looking at the angular distribution for a two-domain surface in the plane perpendicular/parallel to the dimer bonds containing the normal of the surface ͑like in the calculations of Inanaga et al and the available experimental results 1,4,5 ͒, it is shown that the angular distribution can be fitted with a cos 11.5 ͑ f −32°͒ + cos 11.5 ͑ f +32°͒ function, rather than with a cos 2 ͑ f ͒ function. Consequently, the angular distributions simulated with the LEPS PES developed by Kratzer and used by Inanaga et al are not in agreement with the measurements of Inanaga et al 1 or Bisson et al 4,5 Most likely, additional physical processes not covered by the LEPS PES contribute to these measured angular distributions.…”

Growing Fragmented Potentials for Gas–Surface Reactions: The Reaction between Hydrogen Atoms and Hydrogen-Terminated Silicon (111)

“…The reconstructed Si(001) surface is the most commonly studied, though studies including the reconstructed Si(111)-(7 × 7) surface suggest that the reaction mechanisms for H 2 adsorption are not strongly dependent on the details of the silicon surface . The dynamics of the reaction between hydrogen atoms and hydrogen-terminated Si(001) has been studied using periodic DFT and model potentials. − This reaction has also been studied experimentally, using isotopic labeling. − On the hydrogen-terminated Si(001) surface, the Eley–Rideal abstraction of H 2 occurs barrierlessly.…”

Effect of hydrogen on the microstructure evolution of nanocrystalline silicon

“…This potential accurately describes the geometry and the formation energetics of interstitial H in c-Si. 20,21 In order to further establish the reliability of the adopted force-field, we investigated the mobility of an isolated hydrogen atom in bulk c-Si and in a-Si, separately. In particular we evaluated its diffusivity D(T ) by calculating the corresponding mean square displacement and we obtained an activation energy for H migration of 0.44 eV (1.34 eV) in c-Si (a-Si).…”