標題: | Ab Initio Chemical Kinetics for the Thermal Decomposition of SiH4 (+) Ion and Related Reverse Ion-Molecule Reactions of Interest to PECVD of a-Si:H Films |
作者: | Nguyen, T. N. Lee, Y. M. Wu, J. S. Lin, M. C. 機械工程學系 應用化學系 Department of Mechanical Engineering Department of Applied Chemistry |
關鍵字: | PECVD;Silicon thin film;SiH4+;Mechanism;Kinetics |
公開日期: | 1-七月-2017 |
摘要: | The thermal unimolecular decomposition of SiH4 (+) ion and its related reverse reactions, SiH3 (+) + H and SiH2 (+) + H-2, have been investigated by ab initio molecular orbital and quantum statistical variational RRKM theory calculations. The potential energy surface has been calculated at different levels of theory; the results at the highest level, CCSD(T)/CBS//CCSD(T)/6-311++G(3df,2p), show that the decomposition of SiH4 (+) can mainly occur via a barrierless channel giving SiH2 (+) + H-2 lying 11.8 kcal/mol above the reactant, or via a transition state forming SiH3 (+)center dot center dot center dot H complex to be followed by a barrierless decomposition yielding SiH3 (+) + H lying 23.5 kcal/mol above the reactant. Barrierless processes were calculated using the CASPT2 and CASSCF methods with the 6-311++G(3df,2p) basis set and fitted with Morse potentials. The rate constants were predicted by solving master equations based on the RRKM theory at the E,J-resolved level; the results show that the channel SiH4 (+) -> SiH2 (+) + H-2 is predominate under PEVCD conditions. For H- and H-2-capturing by SiH3 (+) and SiH2 (+) ions, respectively, the rate constants were found to be weakly dependent on temperature at the high-pressure limit and decrease rapidly with pressure. The calculated heats of formation of the SiH (x) (+) (x = 2-4) ions are in close agreement with available thermochemical data. |
URI: | http://dx.doi.org/10.1007/s11090-017-9825-7 http://hdl.handle.net/11536/145700 |
ISSN: | 0272-4324 |
DOI: | 10.1007/s11090-017-9825-7 |
期刊: | PLASMA CHEMISTRY AND PLASMA PROCESSING |
Volume: | 37 |
起始頁: | 1249 |
結束頁: | 1264 |
顯示於類別: | 期刊論文 |