Characterization of Al_2O_3/ZrO_2 nano multilayer thin films prepared by pulsed laser deposition

摘要

Microstructural characterization of pulsed laser deposited Al_2O_3/ZrO_2 multilayers on Si (100) substrates at an optimized oxygen partial pressure of 3 × 10~(-2) mbar and at room temperature (298 K) has been carried out. A nanolaminate structure consisting of alternate layers of ZrO_2 and Al_2O_3 with 40 bi-layers was fabricated at different zirconia layer thicknesses (20,15 and 10 nm). The objective of the work is to study the effect of ZrO_2 layer thickness on the stabilization of tetragonal ZrO_2 phase for a constant Al_2O_3 layer thickness of 5nm. The Al_2O_3/ZrO_2 multilayer films were characterized using high temperature X-ray diffraction (HTXRD) in the temperature range 298-1473 K. The studies showed that the thickness of the zirconia layer has a profound influence on the crystallization temperature for the formation of tetragonal zirconia phase. The tetragonal phase content increased with the decrease of ZrO_2 layer thickness. The cross-sectional transmission electron microscope (XTEM) investigations were carried out on a multilayer thin films deposited at room temperature. The XTEM studies showed the formation of uniform thickness layers with higher fraction of monoclinic and small fraction of tetragonal phases of zirconia and amorphous alumina.