A combinatorial chemical beam epitaxy technique was used to optimize deposition of (001) lithium niobate thin films on {001} sapphire substrates. Lithium tert-butoxide [Li(OBut)] and niobium tetra-ethoxy di-methyl-amino-ethoxide [Nb(OEt)(4)(dmac)] were used as precursors. The highest quality films obtained exhibited rocking curve full-width at half-maximum values of about 0.03 degrees and lithium contents {[Li]/[(Li)) + (Nb)]} larger than 48 (mol %) estimated by Raman spectroscopy. High-resolution transmission electron microscopy observations revealed that the lithium niobate film consists of a buffer layer (thickness <8 nm) with a high density of defects above which the epitaxial lithium niobate film was obtained. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3519843] All rights reserved.