Surface damage in the submonolayer growth of carbon on Si(111)7×7 by means of the laser ablation deposition technique

Carbon was deposited on the Si(111)7×7 reconstructed surface at room temperature under ultrahigh vacuum conditions, by the pulsed laser deposition technique. The laser power density was 1010 W/cm2. Scanning tunneling microscope images at submonolayer coverages revealed damage on the surface in the form of vacancies, clusters of vacancies, and displaced atoms, avoiding the formation of a crystalline interface. The magnitude of the damage and the low proportion of fast ionized species measured in the plume indicated that the kinetic energy of the nonionized particles was much larger than that produced in a thermal evaporation process. The combination of ion scattering spectroscopy and Auger electron spectroscopy suggested that carbon deposited by this technique grew implanted in the subsurface. Further coverages above 1 ML showed a moderate increase in the roughness of the surface from 0.8 A root mean square (rms) of the clean Si(111) reconstructed surface to 1.3 A rms above 1 deposited ML of carbon.