Copper overlayers with thicknesses up to several tens of angstroms have been vapor deposited at various substrate temperatures onto rutile ${\mathrm{TiO}}_2$(110) surfaces that have different defect concentrations. The metal films have been studied by means of ${\mathrm{He}}^{+}$ low-energy ion scattering, x-ray photoelectron spectroscopy, and LEED (low-energy electron diffraction). Our measurements clearly show that Volmer-Weber growth (formation of three-dimensional crystallites) occurs even at sample temperatures as low as 160 K. Defects created by sputtering the substrate prior to Cu deposition do not influence the subsequent growth of the Cu films. The clusters are oriented with their (111) orientation parallel to the surface as confirmed by LEED. During low-temperature annealing, a coarsening of the crystallites takes place. The size of the clusters and the coverage have been modeled using simple assumptions about their shape. An average thickness of approximately 10 Å is needed to cover half of the sample with Cu. The growth mode can be attributed to a very weak interaction between Cu and the substrate.

• Received 2 July 1992

DOI:https://doi.org/10.1103/PhysRevB.47.3868