<title>Growth of lithium niobate thin films by solid source MOCVD</title>

Abstract

Lithium niobate (LiNbO3) epitaxial thin films have been grown on c-plane sapphire and LiTaO3 (LT) substrates using solid-source MOCVD. The structural quality of LiNbO3 (LN) films grown on LT was found to be higher than for films grown on sapphire. Films on LT have a single in-plane orientation over a wide range of deposition temperatures (500 degree(s) to 750 degree(s)C), while growth on sapphire often leads to a small percentage of 60 degree(s) misoriented grains. The surface roughness of LN films on LT substrates is also much less than for films deposited on c-sapphire under similar conditions. While sapphire is a less suitable substrate for the deposition of optical quality films, it has provided an opportunity to study the effects of surface microstructure on film quality. Our findings are described. Prism- coupled, thin film analysis has revealed optical losses as low as 2 dB/cm (TMo mode) in 1000 angstroms thick LN films deposited on c-sapphire and 5 approximately 6 dB/cm (TEo mode) in 5000 angstroms films deposited on LT. Using LT, we have been able to deposit high crystalline quality LN films with very smooth surfaces below the Curie temperature of the substrate (600 degree(s)C), and etching techniques have revealed that the polarity of these films follows that of the substrate. This result suggests the possibility of depositing LN on periodically poled LT substrates for quasi-phase matched optical interactions.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.