| Growth stresses of electron-beam deposited, homoepitaxial, yttria-stabilized zirconia (YSZ) thin films were measured in situ as a function of substrate temperature (400--800°C) and deposition rate (0.15--2.0 A/s) using a multi-beam laser curvature measurement system. The film microstructure was studied by transmission electron microscopy and x-ray diffraction. The growth stresses were tensile and ranged from 140 MPa to 1.3 GPa. In films with higher stress, the microstructure consisted of a regular array of voids between columnar grains of YSZ. The concentration and size of these voids was a function of substrate temperature and deposition rate, and increased as the film stress increased. X-ray and electron diffraction showed that the films were fully epitaxial, with some small-angle misorientation of the sub-grains in the high stress films. A model based on kinetic roughening accounts for the generation of stress and the void microstructure. Oxygen vacancy diffusion in the substrate can be measured from the variation in substrate curvature during and after the deposition of oxygen-deficient YSZ films. |
