Ab initio calculation of hydrogen abstraction energetics from silicon hydrides

Growth Processes of Hydrogenated Amorphous Silicon

The surface and subsurface processes occurring during the growth of a-Si:H are analysed to understand why dangling bond defects and weak Si-Si bonds form. We argue that hydrogen elimination to form the Si-Si network is the rate limiting process at low temperature, and this leads to the creation of weak Si-Si bonds. Dangling bonds form subsequently from weak bonds by a defect pool type process. Plasma processes, such as ion bombardment, which dehydrogenate the surface layers, can reduce the weak bond density.

Stability Of Silicon-Oxygen-Fluorine And Carbon-Fluorine LOW-K DIELECTRICS WITH RESPECT TO ATTACK BY WATER

Ab initio configuration interaction calculations have been previously used to account for the relatively large decreases in the static dielectric constant of Si-O-F alloys with low alloy concentrations of F-atoms, ∼ 22%for F concentrations of ∼ 10 at.%. The present study addresses the stability of these alloy films and carbon-fluorine films with respect to attack of Si-F bonds or C-F bonds by water molecules. The present calculations show that the reaction: H20 + 2 Si-F - 2 HF + Si-O-Si is exothermic by about 0.7 eV. However, the reaction of H20 + 2 C-F - 2 HF + CO-C is calculated to be endothermic by 1.6 eV. Our calculations focus on the reaction energetics and geometries as a function of the distance between the F-atoms of the Si-F and C-F groups and water molecule.

Ab Initio Thermochemistry of the Hydrogenation of Hydrocarbon Radicals Using Silicon-, Germanium-, Tin-, and Lead-Substituted Methane and Isobutane

A series of reactions of the type Y. + XH(4) --> YH + .XH(3) and Y'. + HX(CH(3))(3) --> Y'H + .X(CH(3))(3), where Y = H, CH(3); Y' = CH(3), C(CH(3))(3); and X = Si, Ge, Sn, Pb are studied using state-of-the-art ab initio electronic structure methods. Second-order Møller-Plesset perturbation theory; the coupled-cluster singles, doubles, and perturbative triples method; and density functional theory are used with correlation-consistent basis sets (cc-pVNZ, where N = D, T, Q) and their pseudopotential analogs (cc-pVNZ-PP) to determine the transition-state geometries, activation barriers, and thermodynamic properties of these reactions. Trends in the barrier heights as a function of the group IVA atom (Si, Ge, Sn, and Pb) are examined. With respect to kinetics and thermodynamics, the use of a hydrogen attached to a group IVA element as a possible hydrogen donation tool in the mechanosynthesis of diamondoids appears feasible.