Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
ADSORPTION, DESORPTION, AND DECOMPOSITION OF HCL AND HBR ON GE(100) -COMPETITIVE PAIRING AND NEAR-FIRST-ORDER DESORPTION-KINETICS
Autore:
DEVELYN MP; YANG YML; COHEN SM;
Indirizzi:
RENSSELAER POLYTECH INST,DEPT CHEM TROY NY 12180 RENSSELAER POLYTECH INST,DEPT MAT ENGN TROY NY 12180 UNIV HOUSTON,DEPT CHEM HOUSTON TX 77004 LEHIGH UNIV,ZETTLEMOYER CTR SURFACE STUDIES BETHLEHEM PA 18105 GE CO,CORP RES & DEV SCHENECTADY NY 12301
Titolo Testata:
The Journal of chemical physics
fascicolo: 3, volume: 101, anno: 1994,
pagine: 2463 - 2475
SICI:
0021-9606(1994)101:3<2463:ADADOH>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHEMICAL-VAPOR-DEPOSITION; ENERGY-LOSS SPECTROSCOPY; ATOMIC LAYER EPITAXY; SCANNING-TUNNELING-MICROSCOPY; ANGLE-RESOLVED PHOTOEMISSION; PI-BONDED DIMERS; SI(100)-2X1 SURFACE; HYDROGEN ADSORPTION; THERMAL-DESORPTION; H-2 DESORPTION;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
145
Recensione:
Indirizzi per estratti:
Citazione:
M.P. Develyn et al., "ADSORPTION, DESORPTION, AND DECOMPOSITION OF HCL AND HBR ON GE(100) -COMPETITIVE PAIRING AND NEAR-FIRST-ORDER DESORPTION-KINETICS", The Journal of chemical physics, 101(3), 1994, pp. 2463-2475

Abstract

We have investigated the surface chemistry of coadsorbed hydrogen andhalogen atoms on Ge(100), produced by dissociative chemisorption of HCl and HBr, by temperature-programmed desorption. The initial stickingprobability S-0 for HCl decreases from 0.6 at a substrate temperatureof 270 K to 0.05 at 400 K, indicative of a precursor state to adsorption. For HBr S-0 is constant at 0.7 over the same temperature range. Afraction f of adsorbed hydrogen atoms desorb associatively as H-2 near 570 K, while the remaining (1-f) H atoms recombine with adsorbed halogen atoms and desorb as the hydrogen halide (HX) near 580-590 K. The activation energies for desorption of H-2, HCl, and HBr are all approximately 40 kcal/mol. For both HCl and HBr f is 0.7 at low initial coverage and decreases slightly to 0.6 at saturation. The fraction f of adsorbed halogen atoms left on the surface following the competitive desorption of H-2 and HX desorb as the dihalides GeCl2 and GeBr2 near 675and 710 K, respectively. Desorption of H-2, HCl, and HBr occurs with near-first-order kinetics, similar to the behavior of hydrogen adsorbed alone, which we attribute to preferential pairing induced by the pi bond on unoccupied Ge dimers. We introduce and solve a generalized doubly occupied dimer model incorporating competitive pairing of H+H, H+X, and X+X on Ge dimers to explain the near-first-order kinetics. The model quantitatively accounts for both the desorption kinetics and the relative yields of H-2 and HX with pairing energies of approximate to 3 kcal/mol. Implications of the present results for surface thermochemistry, chemical vapor deposition, and atomic layer epitaxy of Ge and Si(100)2X1 surfaces are discussed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/12/20 alle ore 17:36:35