Indentation modulus and microstructural properties of Zirconia – Alumina – Magnesia composite thin films deposited by electron beam evaporation under varying oxygen pressure

Abstract

Zirconia - Alumina – Magnesia (ZrO2Al2O3MgO) ternary composite thin films are used in the fabrication of interference multilayer thin film devices for lasers and photo-physical applications. Optical, structural and morphological properties of such thin films deposited under varying deposition parameters, are reported by researchers. Such thin films possess fascinating spectral stability and optical properties. However, reports on elastic properties that are crucial parameter to assess mechanical stability, are scanty for such thin films. In the present work, ZrO2Al2O3MgO thin films have been deposited by electron beam evaporation under varying oxygen (O2) pressure. Atomic force acoustic microscopy, which is rather new technique, has been employed to estimate indentation modulus of the films. Indentation modulus exhibits a decreasing trend with deposition O2 pressure. Film density measured by grazing incidence X-ray reflectivity, decreases monotonically with O2 pressure. The variation of indentation modulus as well as density has been explained in terms of varying microstructure and mutual concentration of different components of ternary composite thin films. Correlation length, root mean square surface roughness and roughness exponents have been obtained through analysis of height-height correlation function measured by atomic force microscopy. Variation of correlation length corroborates the variation of indentation modulus and film density.