Kinetics of D abstraction with H atoms from the monodeuteride phase on Si(100) surfaces

The abstraction kinetics of D from the monodeuteride phase on Si(100) surfa ces by H atoms was studied at 640 K as a function of the D coverage using d irect product detection. HD and D-2 were observed as products, with D-2 acc ounting for 5.7% of the abstracted D. The KD kinetics does not follow an El ey-Rideal reaction scheme. At the completed monodeuteride layer, the abstra ction probability per incoming H atom is 0.15, corresponding to an abstract ion cross-section of sigma=3 Angstrom(2). The kinetic features of HD and D- 2 can be explained through a hot-atom reaction scenario. Expressing adsorpt ion and abstraction through Kisliuk-type kinetics, it is shown that the abo ve value of the abstraction probability and the initial D sticking probabil ity of 0.5 lead to a saturation coverage of close to unity. The existence o f a recently observed strongly bound state of H was confirmed. D adsorbed o n these sites are abstracted with smaller cross-section than from monodeute ride sites. (C) 1999 Elsevier Science B.V. All rights reserved.