DIFFUSION, NUCLEATION AND ANNEALING OF CO ON THE H-PASSIVATED SI(100)SURFACE

We investigate the diffusion, nucleation and annealing behaviour of Co on H-passivated Si(100) surfaces by scanning tunneling microscopy (ST M). Due to the absence of nucleation sites for silicide formation, the nucleation and growth mode is dominated by the formation of non-epita xial islands which merge by increasing Co coverage theta. The island n umber density N shows a power law dependence on coverage N proportiona l to theta(c) (c = 0.29 +/- 0.03) for room temperature deposition. Ann ealing at temperatures up to similar to 400 degrees C results in small changes of the Co clusters, while deposition at elevated substrate te mperatures (similar to 400 degrees C) results in the formation of fewe r but coarser Co islands. Finally, at higher annealing temperatures (s imilar to 490 degrees C) where H desorption takes place, the formation of two-dimensional islands occurs which are surrounded by an irregula r 2 x n (n > 1) reconstructed surface due to interstitial diffusion of Co into Si. (C) 1998 Elsevier Science B.V. All rights reserved.