ATOMIC-HYDROGEN-INDUCED SELF-ORGANIZATION PROCESSES OF THE IN SI(111)SURFACE PHASES STUDIED BY SCANNING-TUNNELING-MICROSCOPY/

We have investigated the initial processes of the interaction of atomi c hydrogen with the 4 X 1 and the root 31 X root 31 surface phases in the In/Si(111) system at substrate temperature around 300 degrees C us ing scanning tunneling microscopy. It has been revealed that the atomi c-hydrogen-induced self-organization processes of these surface phases are strongly dependent on the substrate Si reconstruction. The adsorp tion of atomic hydrogen on the 4 X 1-In surface, which has a reconstru ction of 2 ML of Si layers, involves removal of In atoms from the surf ace but no Si movement, resulting in the formation of hydrogen-termina ted bared zigzagging Si chains with the preservation of the 4 X 1 peri odicity. On the other hand, the adsorption of atomic hydrogen on the r oot 31 X root 31 surface, which has a reconstruction of 1 ML of Si lay er, exhibits peculiar self-organization processes depending on the hyd rogen exposure: at the initial stage of the hydrogen exposure only the half-unit of the root 31 X root 31 lattice is preferably attacked by hydrogen atoms with the preservation of the root 31 X root 31 periodic ity, while upon prolonged hydrogen exposure, the root 31 X root 31 per iodicity is destroyed as a result of the movement of the Si reconstruc ted layer, forming hydrogen-terminated quasi-ID Si chains. These resul ts suggest the possibility of atomic-hydrogen-induced self-organizatio n of substrate Si atoms. (C) 1998 Elsevier Science B.V. All rights res erved.