SURFACE DAMAGE IN THE SUBMONOLAYER GROWTH OF CARBON ON SI(111)7X7 BY MEANS OF THE LASER-ABLATION DEPOSITION TECHNIQUE

Carbon was deposited on the Si(111)7X7 reconstructed surface at room t emperature under ultrahigh vacuum conditions, by the pulsed laser depo sition technique. The laser power density was 10(10) W/cm(2). Scanning tunneling microscope images at submonolayer coverages revealed damage on the surface in the form of vacancies, clusters of vacancies, and d isplaced atoms, avoiding the formation of a crystalline interface. The magnitude of the damage and the low proportion of fast ionized specie s measured in the plume indicated that the kinetic energy of the nonio nized particles was much larger than that produced in a thermal evapor ation process. The combination of ion scattering spectroscopy and Auge r electron spectroscopy suggested that carbon deposited by this techni que grew implanted in the subsurface. Further coverages above 1 ML sho wed a moderate increase in the roughness of the surface from 0.8 Angst rom root mean square (rms) of the clean Si(111) reconstructed surface to 1.3 Angstrom rms above 1 deposited ML of carbon. (C) 1997 American Vacuum Society.