AVS 50th International Symposium
    Thin Films Wednesday Sessions
       Session TF2-WeA

Paper TF2-WeA6
Electron Cyclotron Resonance Plasma Sputtering Deposition of Highly <001> Textured LiNbO@sub 3@ Thin Films on Si Substrates and Their Electro-Optic Properties

Wednesday, November 5, 2003, 3:40 pm, Room 329

Session: Optical Thin Films and Photovoltaics II
Presenter: H. Akazawa, NTT Microsystem Integration Laboratories, Japan
Authors: H. Akazawa, NTT Microsystem Integration Laboratories, Japan
S. Masaru, NTT Microsystem Integration Laboratories, Japan
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*Electron cyclotron resonance plasma sputtering provides high-quality thin film growth in the spontaneously generated electric field as well as the plasma stream, which carries kinetic energies of 10-30 eV. This technique has been used to grow <001> textured LiNbO@sub 3@ (LN) thin films on Si substrates with a LiNbO@sub 3@ target. Smooth, crack-free films more than 1.2 µmm thick, were obtained. The x-ray diffraction pattern of films grown under optimized conditions revealed a single LiNbO@sub 3@ phase with its <001> direction preferentially oriented along the substrate normal. The LiNb@sub 3@O@sub 8@ phase developed under excess O@sub 2@ gas ambient because of the enhanced re-evaporation of Li@sub 2@O molecules. ICP atomic emission spectroscopy confirmed that the composition is mainly affected by the oxygen partial pressure, but little affected by the growth temperature. Cross-sectional TEM images revealed columnar grains extending from the interface, and the volume fraction of the c-axis oriented domains was about 30%. Double inter-layers, 3-5 nm thick, (possibly a-SiO@sub 2@ and a-LN) were seen between the crystalline LN film and the Si substrate. The refractive index of the LN film was similar to the value of bulk crystal, indicating that the film was densely packed. The current-voltage characteristic was reversible up to the electric coercive force of bulk LN without destroying the insulating property, and the resistance was of the order of 10@super -11@ @ohm@cm below the applied voltage of 2 eV. The electro-optic effect was investigated by spectroscopic ellipsometry. We could detect a @delta@n value in the 10@super -4@ range, which corresponds to 30-20% of the Pockels constant of bulk crystal.