Structure control of pulsed laser deposited ZrO2/Y2O3 films

Structure control in the laser ablation deposition of yttria stabilized zirconia (YSZ) films is explored. A focus was given to a low temperature growth of tetragonal and cubic YSZ films with [001] growth orientation, using surface ion bombardment. Unlike an ion-beam assisted pulsed laser deposition, the ion bombardment was achieved by the acceleration of zirconium ions from the ablation plumes themselves with a negative substrate bias. The large degree of zirconium ionization was obtained by using low pressure Ar backgrounds. Correlation between substrate bias, film lattice parameters, orientation, surface microtopography, stress, and hardness are discussed. Film structural change from nearly amorphous and predominantly (111) oriented to distorted tetragonal and to cubic with (002) orientation were observed as the bias was increased from zero to −300 V in 0.2 Pa Ar environment. The technique was used to produce single-axis oriented YSZ films with a smooth (002) surface and 30 GPa hardness on a number of single and polycrystalline substrates at 100 °C deposition temperature.