High temperature XRD of zirconia/alumina multilayer thin films prepared by pulsed laser deposition

Abstract

ABSTRACT Al 2 O 3 /ZrO 2 multilayers have been deposited on Si(100) substrates by reactive pulsed laser deposition technique. The experiments were performed at an optimized oxygen partial pressure of 3x10 -2 mbar at room temperature. A nanolaminate structure consisting of alternate layers of ZrO 2 and Al 2 O 3 with 40 bi-layers were fabricated with thickness of each layer of zirconia and alumina of 15 nm and 5 nm, respectively. The cross-sectional transmission electron microscope (XTEM) investigations were carried out on a multilayer thin film deposited at room temperature. The XTEM study shows the formation of uniform thickness, higher fraction of monoclinic and small fraction of tetragonal phases of zirconia and amorphous alumina. The ZrO 2 /Al 2 O 3 multilayer film was characterized using high temperature x-ray diffraction (HTXRD) in the temperature range RT-1473 K. The ZrO 2 /Al 2 O 3 multilayer shows a crystallization temperature of 673 K for the formation of tetragonal and monoclinic phases with significant amount of tetragonal phase over the la tter. From the HTXRD profiles, crystalli te size, lattice parameters, and thermal expansion coefficient of the tetragonal phase were calculated. Key words: Thin films, multilayers, alumina, zirconia, pulsed laser deposition, high temperature x-ray diffraction, cross sectional transmission electron microscopy, nanolaminates.