| Autor: |
Comerford DW; School of Chemistry, University of Bristol, Bristol, U.K., Cheesman A, Carpenter TP, Davies DM, Fox NA, Sage RS, Smith JA, Ashfold MN, Mankelevich YA |
| Jazyk: |
angličtina |
| Zdroj: |
The journal of physical chemistry. A [J Phys Chem A] 2006 Mar 09; Vol. 110 (9), pp. 2868-75. |
| DOI: |
10.1021/jp053455p |
| Abstrakt: |
Experimental and modeling studies of the gas-phase chemistry occurring in dilute, hot filament (HF) activated B2H6/H2 and B2H6/CH4/H2 gas mixtures are reported. Spatially resolved relative number densities of B (and H) atoms have been measured by resonance enhanced multiphoton ionization methods, as a function of process conditions (e.g. the HF material and its temperature, the B2H6/H2 mixing ratio, and the presence (or not) of added CH4). Three-dimensional modeling of the H/B chemistry prevailing in such HF activated gas mixtures using a simplified representation of the gas phase chemistry succeeds in reproducing all of the experimentally observed trends, and in illustrating the key role of the "H-shifting" reactions BHx + H <= => BHx-1 + H2 (x = 1-3) in enabling rapid interconversion between the various BHx (x = 0-3) species. CH4 addition, at partial pressures appropriate for growth of boron-doped diamond by chemical vapor deposition methods, leads to approximately 30% reduction in the measured B atom signal near the HF. The modeling suggests that this is mainly due to concomitant H atom depletion near the HF, but it also allows us a first assessment of the possible contributions from B/C coupling reactions upon CH4 addition to HF activated B2H6/H2 gas mixtures. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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