Abstraction of Si and SiHx (x = 1, 2, 3) adsorbed on Cu(100) surfaces with gaseous H(D) towards silane

The interaction of silane and disilane with Cu(1 0 0) surfaces was studied in the temperature range 77-650 K with thermal desorption and Auger electron spectroscopies. Silane admission to Cu(I 0 0) at low temperatures initially leads to a complete decomposition of the silanes into adsorbed Si and H. Close to saturation of the surface with H, SiHx species remain intact on the surface. They were identified as SiH3 and to a smaller extent SiH2 by monitoring the silane abstraction products and their kinetics during admitting gaseous D to the surface between 77 and 200 K. Silane desorption through recombination of SiH3 and SiH2 with adsorbed H occurs around 157 and 224 K, respectively. After hydrogen desorption around 300 K a Si covered surface remains, which can be converted to a clean Cu(I 0 0) surface by activating Si bulk diffusion around 700 K. Adsorbed Si is abstracted from the surface below 200 K by gaseous H via formation of silane through a sequence of four hydrogenation steps. The first hydrogenation reaction is rate determining g and is significantly accelerated by increasing the temperature between 77 and 200 K. Above 200 K a thermally unstable SiHx species blocks the abstraction reaction. The reaction kinetics phenomenology is in accordance with an Eley-Rideal scenario. (C) 2001 Elsevier Science B.V. All rights reserved.