Optical and mechanical properties of nanolaminates of zirconium and hafnium oxides grown by atomic layer deposition

Nanolaminates of ZrO2 and HfO2 were grown by atomic layer deposition, using metal halides and water as precursors, on silicon and fused quartz substrates at 300 degrees C. The crystalline phase composition, optical refraction, and mechanical performance of the multilayers were influenced by the relative contents of the constituent metal oxides. The crystal growth in as-deposited HfO2 dominantly led to the monoclinic phase, whereas ZrO2 was partially crystallized as its metastable and hard tetragonal polymorph. The hardness and elasticity of the nanolaminate structures could be modified by varying the amounts of either oxide contributing to the crystallographic order formed in the solid films. The refractive indexes depended on the nanolaminate structure.