Evolution of Yttrium Aluminum Garnet Films by Solid-State Reaction

Abstract

ABSTRACTYttrium aluminum garnet (YAG) films were produced by reacting thin Y2O3 layers with single-crystal Al2O3 substrates. Y2O3 films were deposited using pulsed-laser deposition (PLD), which produced smooth textured films on specially prepared (0001) α-Al2O3 substrates. Solid-state reaction of the Y2O3 with the Al2O3 was induced by specific heat treatments. Transmission-electron microscopy was used to characterize the reaction products of each heat treatment. For a reaction temperature of 1200°C, cross-sectional TEM specimens revealed the development of Monoclinic Y4Al2O9 at the interface between the Y2O3 and the Al2O3. Development of YAG was seen to occur at the interface between the Al2O3 and the Y4Al2O9 for a slightly higher reaction temperature of 1250°C. The Metastable Y4Al2O9 phase and the Y2O3 phase were found to be consumed at higher reaction temperatures to form the equilibrium Y3Al5O12 (YAG) phase. The Morphology of the YAG film was characterized by scanning-electron microscopy.