| AVS 54th International Symposium | |
| Thin Film | Wednesday Sessions |
| Session TF-WeA |
| Session: | Oblique Angle Deposition |
| Presenter: | H. Wormeester, University of Twente, The Netherlands |
| Authors: | H. Wormeester, University of Twente, The Netherlands F.L.W. Rabbering, University of Twente, The Netherlands F.G. Stoian, University of Twente, The Netherlands R. Gastel, University of Twente, The Netherlands B. Poelsema, University of Twente, The Netherlands |
| Correspondent: | Click to Email |
Oblique incidence deposition is widely used for the preparation of anisotropic structures in thin films with interesting magnetic or optical properties. We have studied the consequences of oblique incidence deposition for the morphology of the growth-front for a "prototypical" system Cu/Cu(001). According to previous electron diffraction measurements, deposition at grazing incidence leads to the evolution of ripples, oriented perpendicular to the plane of incidence of the atom beam. Here we present new experimental results, obtained with high resolution low energy electron diffraction and STM, for various stages in the formation of the ripples. At grazing incidence, experiments indeed show that initially the ripples are oriented perpendicular to the plane of incidence of the atom beam. At more progressed stages of growth and at very grazing incidence deposition experiments show a deviation from the ripple formation. The ripple formation has also been studied with kMC simulations, which support (or actually predicted) experimentally observed changes in ripple formation at later stages in growth. The relevant activation barriers for intra- and interlayer diffusion processes in these simulations have been tuned to describe quantitatively(!) experimentally observed morphologies in a wide range of temperatures (150-300 K) and coverages (up to 40 ML). An essential role is played by both long and short range attractive interactions between the incoming particle and the substrate. The kMC simulations show a change in ripple orientation from perpendicular to the plane of incidence to parallel to this plane around a coverage of 40 ML at a temperature of 250 K for a deposition angle of 80°. At 230K this orientation transition has been found to occur at a much earlier stage in growth. At more grazing incidence deposition only ripples parallel to the plane of incidence have been found to develop and no change in orientation has been seen for smaller deposition angles. This orientation change is related to the very strong roughening of the growth front for grazing incidence growth and the corresponding heterogeneity of incident flux.