Growth mode of Pt clusters deposited on γ-Al2O3(1 1 1)/NiAl(1 1 0): a TEM study

Pt clusters deposited on a γ-Al2O3(1 1 1)/NiAl(1 1 0) substrate under ultra-high vacuum conditions were studied by transmission electron microscopy. Cluster size and density were varied by altering substrate temperature during deposition and the platinum coverage. The average cluster size was found to increase monotonically with increasing platinum coverage whereas the cluster density exhibits a maximum. It was also found that the deposition temperature strongly affects the cluster growth. When the temperature increases between 300 and 600 K, the aspect ratio (the relationship between the cluster height and its lateral size) increases as well.