Growth and electronic properties of Ti nanoislands on Au(111)

The initial growth of titanium nanoislands on the reconstructed Au(111) surface was investigated by Scanning Tunneling Microscopy and Scanning Tunneling Spectroscopy (STM/STS). Ti atoms evaporated onto room temperature substrate start to nucleate preferentially at the elbows of the Au(111) herringbone reconstruction; however ordered nucleation is accompanied by an early occurrence of out-of-elbow islands. Titanium islands are irregularly shaped, composed of smaller subunits as grains of about 1-2 nm2 and their growth leads to a distortion of the underlying gold surface. We observe a retarded coalescence of titanium first layer islands with respect to similar systems. Comparing the experimental data with a diffusive model quantitative information about the interlayer diffusion of the first two layers is obtained. STS spectra and differential conductivity maps show peculiar electronic features outlining an important interaction between Ti atoms and the Au(111) surface.