INFLUENCE OF SUBSTRATE-TEMPERATURE ON THE PROPERTIES OF ARGON-ION-ASSISTED-DEPOSITED CEO2 FILMS

The effects of argon ion bombardment and substrate temperature on the optical and structural properties of electron-beam-evaporated CeO2 films have been investigated. The refractive index, extinction coefficient, packing density, inhomogeneity and structure are reported for ion energies in the range 300-700 eV, and ion current densities in the range 50-220 muA cm-2. The substrate temperature was varied between ambient and 300-degrees-C. Argon ion bombardment of CeO2 films deposited at ambient temperature has significantly influenced the extinction coefficient of the films. The combined effect of elevated substrate temperature, ion energy and ion current density resulted in a decrease in the extinction coefficient. The maximum refractive index (n = 2.45 at lambda = 550 nm), nearly unity packing density and absorption-free films have been obtained for a rate of deposition of 0.3 nm sec-1, an ion energy of 600 eV, an ion density of 220 muA cm-2 and a substrate temperature of 300-degrees-C. Argon ion bombardment and an elevated substrate temperature resulted in an orientation change from (111) to (220).