Abstract
We have grown high density Co clusters with a narrow-sized distribution on the Si3N4(0001)-(8×8) surface. In the submonolayer regime, Co clusters tend to keep a certain size (~1.45 nm in diameter) irrespective of coverage. With increasing coverage above 0.92 ML, two new clusters with certain but larger sizes are formed. This novel growth behaviour can be explained by the quantum size effect [Phys. Rev. Lett. 90 (2003) 185506]. It is found that the Co cluster size distribution can be improved by post annealing. Even at high temperature (700°C), no reaction of Co with Si3N4 is observed, indicating that Si3N4(0001)-(8×8) is a promising substrate for growth of magnetic nanostructures.