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Epitaxial Variants and Grain Boundary Structures in Heteroepitaxial Lithium Tantalate on Basal Sapphire

Published online by Cambridge University Press:  10 February 2011

Robert A. Bellman  and
Rishi Raj
Robert A. Bellman
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
Rishi Raj
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
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Abstract

Single crystal heteroepitaxial ferroelectric films are desired for non-linear optical applications to maximize the electro-optic coefficient and minimize waveguide losses. In this study, lithium tantalate films were deposited on (0001) sapphire from lithium hexaethoxytantalate by chemical beam epitaxy. Characterization showed that films had nearly stoichiometric composition, epitaxial orientation, and a high degree of crystalline perfection. However, the films exhibited high optical waveguide losses. Additional characterization by TEM revealed that the films had a two dimensional grain structure with epitaxial variants related by translation and a twin orientation to the substrate. To better understand the nature of the heteroepitaxial growth of lithium tantalate on (0001) sapphire, a model was developed to explain the observed epitaxial orientations, misfit dislocation networks, and grain boundary structures of lithium tantalate on (0001) sapphire.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 441: Thin Films – Structure and Morphology , 1996 , 125
Copyright
Copyright © Materials Research Society 1997

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