Abstraction of hydrogen by SiH3 from hydrogen-terminated Si(001)-(2x1) surfaces

We present the dynamics and energetics of an Eley-Rideal reaction by which SiH3 radicals impinging on a H-terminated Si(001)-(2 x 1) surface during pl asma deposition abstract hydrogen atoms from the surface and return to the gas phase as silane molecules. The reactions were observed during classical molecular-dynamics simulations of hydrogenated amorphous silicon depositio n from SiH3, radicals impinging on H-terminated Si(001)-(2 x 1) surfaces ma intained at temperatures over the range 500 K less than or equal to T less than or equal to 773 K. The H-abstraction reaction introduces dangling bond s at the surface that impinging SiHx (0 less than or equal to x less than o r equal to 3) radicals can attach to; thus, it is a crucial reaction for de position. The computed activation energy barrier for the reaction and the e xothermic reaction energy are 0.09 eV and 0.23 eV, respectively. The energe tics of the reaction as computed based on an empirical classical potential are in good agreement with density-functional-theory pseudopotential calcul ations using a cluster model. (C) 1998 Elsevier Science B.V. All rights res erved.