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Titolo:
REACTION DYNAMICS OF MOLECULAR-HYDROGEN ON SILICON SURFACES
Autore:
BRATU P; BRENIG W; GROSS A; HARTMANN M; HOFER U; KRATZER P; RUSS R;
Indirizzi:
MAX PLANCK INST QUANTUM OPT D-85740 GARCHING GERMANY TECH UNIV MUNICH,DEPT PHYS D-85747 GARCHING GERMANY MAX PLANCK GESELL,FRITZ HABER INST D-14195 BERLIN GERMANY TECH UNIV DENMARK,CTR ATOM SCALE MAT PHYS DK-2800 LYNGBY DENMARK TECH UNIV DENMARK,DEPT PHYS DK-2800 LYNGBY DENMARK
Titolo Testata:
Physical review. B, Condensed matter
fascicolo: 8, volume: 54, anno: 1996,
pagine: 5978 - 5991
SICI:
0163-1829(1996)54:8<5978:RDOMOS>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUMERICALLY STABLE SOLUTION; COUPLED-CHANNEL EQUATIONS; SCANNING TUNNELING MICROSCOPY; INTERNAL-STATE DISTRIBUTIONS; PHONON-ASSISTED STICKING; PI-BONDED DIMERS; H-2 DESORPTION; SI(100)-2X1 SURFACE; ATOMIC-HYDROGEN; RECOMBINATIVE DESORPTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
86
Recensione:
Indirizzi per estratti:
Citazione:
P. Bratu et al., "REACTION DYNAMICS OF MOLECULAR-HYDROGEN ON SILICON SURFACES", Physical review. B, Condensed matter, 54(8), 1996, pp. 5978-5991

Abstract

Experimental and theoretical results on the dynamics of dissociative adsorption and recombinative desorption of hydrogen on silicon are presented. Using optical second-harmonic generation, extremely small sticking probabilities in the range 10(-9)-10(-5) could be measured for H-2 and D-2 on Si(111)7X7 and Si(100)2X1. Strong phonon-assisted sticking was observed for gases at 300 K and surface temperatures between 550K and 1050 K. The absolute values as well as the temperature variation of the adsorption and desorption rates show surprisingly little isotope effect, and they differ only little between the two surfaces. These results indicate that tunneling, molecular vibrations, and the structural details of the surface play only a minor role for the adsorptiondynamics. Instead, they appear to be governed by the localized H-Si bonding and Si-Si lattice vibrations. Theoretically, an effective five-dimensional model is presented taking lattice distortion, corrugation,and molecular vibrations into account within the framework of coupled-channel calculations. While the temperature dependence of the sticking is dominated by lattice distortion, the main effect of corrugation is a reduction of the preexponential factor by about one order of magnitude per lateral degree of freedom. Molecular vibrations have practically no effect on the adsorption/desorption dynamics itself, but lead to vibrational heating in desorption with a strong isotope effect. Ab initio calculations for the H-2 interaction With the dimers of Si(100)2X1 show properties of the potential surface in qualitative agreement with the model, but its dynamics differs quantitatively from the experimental results.

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Documento generato il 02/12/20 alle ore 16:42:38