STRUCTURAL, OPTICAL AND ELECTRONIC-PROPERTIES OF MIXED DIELECTRIC FILMS

Homogeneous and inhomogeneous mixed films of the type X-ZrO2 (X = MgF2, SiO2) applicable to interference optics were deposited on heated and unheated substrates by coevaporation using separate electron-beam evaporators with closed-loop rate control and thickness monitoring by quartz crystal oscillators. Optical and structural properties of homogeneous mixed films have been studied by means of optical spectroscopy (uv, vis, ir), X-ray diffraction and RBS. The dependence of refraction index on film composition was compared with well-known mixing models. For deposition on unheated substrates best agreement was obtained with the Lorentz-Lorenz model. On heated substrates an anomaly of refraction index dependent on SiO2-ZrO2 film composition can be interpreted as a packing density effect. Infrared-absorption bands at wavenumbers of 980 cm-1 and 910 cm-1 refer to SiOZr bonds in the films. In MgF2-ZrO2 mixed films, which were deposited on heated substrates, strong uv-vis absorption is observed. Further, the influence of ZrO2 volume fraction on optical gap energy Eg has been studied. © 1990.