Epitaxial Growth of MgO-doped Lithium Niobate Thin Films by Metalorganic Chemical Vapor Deposition

摘要

Epitaxial MgO-doped lithium niobate [LiNbO_3 (LN)] single-crystal thin films with a good surface morphology and crystallinity were grown on lithium tantalate [LiTaO_3 (LT)] substrates by low-pressure metalorganic chemical vapor deposition (MOCVD). Dipivaloylmethanatolithium [Li(C_(11)H_(19)O_2); Li(DPM)], pentaethoxyniobium [Nb(OC_2H_5)_5; Nb(OEt)_5] and bisacetylacetonatomagnesium [Mg(C_5H_7O_2)_2; Mg(Acac)_2] were used as volatile metalorganic precursors. The crystallinity of the films was investigated by X-ray diffraction measurements. Reciprocal space mapping indicated that good epitaxial growth had been achieved. The film surface was sufficiently smooth to act as a waveguide. The ordinary and extraordinary refractive indices (n_o and n_e) of these as-grown MgO-doped LN thin films were measured to be n_o = 2.2844 and n_e = 2.1908 at 633 nm, respectively, which were close to those of 3mol% MgO-doped stoichiometric LN.