Controlling size distributions of copper islands grown on TiO2(1 1 0)-(1×2)

The growth of Cu islands (0.03–3.4 ML) on a partially reconstructed TiO2(1 1 0) surface was investigated by scanning tunneling microscopy. These studies show that the island size distributions can be controlled by varying the diffusion (D) to flux ratio (F), with the smallest values of D/F corresponding to the most uniform size distributions. Cu diffusion on the reconstructed surface is slow and anisotropic at room temperature, resulting in post-deposition growth of the Cu islands and apparent clustering of islands at high coverage. The weak dependence of island density on flux suggests that nucleation at defects plays a role in growth of Cu on titania. The most striking characteristic of Cu growth on titania is that islands continue to nucleate up to the highest coverages studied, and consequently the increase in coverage has less of an effect on the island sizes. Despite the continued nucleation at high coverages, island size distributions are not unusually broad at room temperature and are comparable to those for metal on metal epitaxy.