Diffusion, nucleation and annealing of Co on the H-passivated Si(100) surface

Abstract

We investigate the diffusion, nucleation and annealing behaviour of Co on H-passivated Si(100) surfaces by scanning tunneling microscopy (STM). Due to the absence of nucleation sites for silicide formation, the nucleation and growth mode is dominated by the formation of non-epitaxial islands which merge by increasing Co coverage θ. The island number density N shows a power law dependence on coverage N∝ θ c ( c=0.29±0.03) for room temperature deposition. Annealing at temperatures up to ∼400°C results in small changes of the Co clusters, while deposition at elevated substrate temperatures (∼400°C) results in the formation of fewer but coarser Co islands. Finally, at higher annealing temperatures (∼490°C) where H desorption takes place, the formation of two-dimensional islands occurs which are surrounded by an irregular 2× n ( n>1) reconstructed surface due to interstitial diffusion of Co into Si.