Self-regulated Ni cluster formation on the TiO2(1 1 0) terrace studied using scanning tunneling microscopy

We have studied the growth mode and morphology of Ni clusters on a TiO2(1 1 0) surface with a wide terrace using scanning tunneling microscopy (STM) at a low coverage (less than 3 atoms nm−2). The Ni clusters are formed on the terrace at the low coverage of 0.2 atoms nm−2. Their average dimensions are constant in three directions up to 1 atoms nm−2. The Ni clusters have an oval shape with average sizes of 1.8 nm (along [0 0 1]) × 1.4 nm (along [ 1 1 ¯ 0 ] ) × 0.38 nm (in the [1 1 0] directions). Above the coverage of 1.0 atoms nm−2, an increase in the cluster height occurs, retaining an almost constant lateral size. It is proposed that the interaction of the Ni cluster and the support surface regulates the Ni cluster size.