Morphological change of Co-nanodot on SiO2 by thermal treatment

Morphological changes of Co nanodots on SiO2 layers by thermal treatment have been investigated. Co nanodots were formed by molecular beam deposition of Co on SiO2 layers with substrate temperatures (30–600 °C) and subsequent post-annealing (500–800 °C). For samples deposited at low temperatures (30–280 °C), the diameter and the density of nanodots increased and decreased, respectively, with increasing post-annealing temperature. On the other hand, the diameter and the density of nanodots scarcely changed by post-annealing for samples deposited at high temperatures (430–600 °C). These morphological changes by the post-annealing can be explained on the basis of the stress relaxation in the deposited Co films.