Shoji Morita

Flow in oxide melts in a high magnetic field

Abstract Magnetic-field-applied Czochralski equipment for oxide growth was designed and constructed. Using this equipment, it was possible to apply three types of magnetic fields in oxide melts. The flow in an oxide melt such as LiNbO 3 and TiO 2 in a high magnetic field was observed. It was found that the flows in oxide melts were very different from those in a semiconductor melt.

Growth of gadolinium indium gallium garnet (GInGG) single crystal by the floating zone method

Abstract A new garnet Gd 3 In 2 Ga 3 0 12 (GInGG) was synthesized by the sintering method from Gd 2 0 3 , In 2 0 3 and Ga 2 0 3 . Single crystals of Gd 3 In 2 Ga 3 0 12 were grown by the floating zone method. The obtained crystals were colorless and transparent. Their lattice constants were measured to be 1.266 nm.

The growth of (TbxGd1 − x)AlO3 single crystals by the Czochralski method

(Tb x Gd 1-x )AlO 3 single crystals were grown by the Czochralski method. The crystals grown from Tb-rich melts under a reducing atmosphere were both twin and crack free. It is generally difficult to grow single crystals without cracks from Gd-rich melts. The optical properties of the crystals could be controlled by substituting Gd for Tb.

The growth of DyAlO3 single crystals by Czochralski method

Perovskite-type rare-eart aluminate and gallate crystals are suitable as substrates for high T c oxide superconductor film. We were able to grow dysprosium aluminate DyAlO 3 (DAO) single crystals by the Czocbralski method. The obtained crystals bad no cracks and no twin boundaries

Numerical modeling of silicon film deposition in very-high-frequency plasma reactor

We present a numerical modeling of plasma-enhanced chemical vapor deposition (PECVD) of silicon film from SiH/sub 4/ and H/sub 2/ gas mixtures in very-high-frequency (VHF) plasma reactor. The model is composed by electron impact, gas-phase, and surface reactions in a well-mixed reactor model. A set of plasma parameters such as electron density, electron temperature and electron impact reaction rates is determined separately by nonequilibrium plasma model and used as inputs for well-mixed reactor models. The gas-phase reactions include electron impact and neutral-neutral reactions. Some of unknown rates of surface reactions are determined using quantum chemical calculations and transition state theory. In well-mixed reactor models, concentrations of each chemical species are calculated in a steady state condition using mass conservation equation uniformed through the reactor. Numerical results of growth rate as a function of plasma reactor operating parameters show good agreement with experimental ones. Finally optimal operating parameters are investigated using our model combined with design of experiments and optimization techniques.