Optical properties of alumina and zirconia thin films grown by pulsed laser deposition

Sintered targets of ZrO2 and Al2O3 are ablated by KrF excimer laser radiation. The processing gas atmosphere consists of O2 at typical pressures of 10(exp -3)-1 mbar. Films with a thickness of 200-700 nm are deposited on a Pt/Ti/Si multilayer substrate. The analytical techniques used for the determination of structural characteristics of the films are X-ray diffraction and electron microscopy. The thickness and the complex refraction index are determined by ellipsometry by fitting a model for the film geometry to the measured data. The optical film thickness at different wavelengths is determined using interference reflection photometry. The investigations concentrate on the influence of the oxygen pressure, the target-to-substrate distance and the laser fluence on the refraction index of the films, which is correlated with the film density. The compaction of the films is achieved by particles impinging with kinetic energies above 30 eV on the growing surface. The kinetic energy of the particles depending on the processing parameters is modelled and related to the resulting film properties.