Growth of RuO2 thin layer on Ru(101¯0) studied by scanning tunneling microscopy

Investigations of growth of RuO2 thin layer on Ru(101¯0) by oxidation were performed by means of scanning tunneling microscopy (STM). The results showed that the morphologies and the structures of RuO2 thin film grown on Ru(101¯0) depend crucially on the O2 pressure and reaction temperature. At a sample temperature of about 600 K and an O2 pressure of 5 × 10−6 mbar, the oxidation of Ru(101¯0) leads to formation of Ru-O chain structures, which can be attributed to the dynamical hindrance arisen from the repulsive dipolar interaction. This dynamical hindrance can be overcome, and the RuO2(1 0 0)-(1 × 1) phase, together with the RuO2(1 0 0)-c(2 × 2) patch, can be formed by increasing O2 pressure. Further increasing the sample temperature up to 760 K at the same O2 pressure, the oxidation results in formation of a RuO2(1 1 1) film over the RuO2(1 0 0) thin layer.