Improved solid phase epitaxial growth of lithium tantalate thin films on sapphire, using a two-step metalorganic chemical-vapor deposition process

Abstract

Epitaxial lithium tantalate thin films were grown on sapphire substrates by metal-organic chemical-vapor deposition using a two-step growth process. After an initial thin (≊30–100 Å thick) amorphous buffer layer of LiTaO3 was deposited and annealed to induce crystallization by solid phase epitaxy (SPE), a second, thicker amorphous lithium tantalate layer was deposited and also crystallized using SPE. The use of the buffer layers substantially improved the crystalline quality of the heteroepitaxial films, with the thickest buffer layer providing the best results. The films were characterized by ion channeling, x-ray diffraction and scanning electron microscopy.