Roughness of glancing angle deposited titanium thin films: an experimental and computational study.

The characterization of roughness at the nanoscale by the means of atomic force microscopy (AFM) was performed on high aspect ratio glancing angle deposited titanium thin films. With the use of scanning electron microscopy as well as x-ray photoelectron spectroscopy, it was shown that the AFM measurements gave rise to incorrect roughness values for the films consisting of the highest aspect ratio structures. By correcting for this experimental artefact, the difference between the saturated roughness value of a film grown with conventional physical vapour deposition and films grown with a glancing angle of deposition was shown to behave as a power law function of the deposition angle, with a saturated roughness exponent of κ = 7.1 ± 0.2. This power law scaling was confirmed by three-dimensional molecular dynamics simulations of glancing angle deposition, where the saturated roughness exponent was calculated to κ = 6.7 ± 0.4.