Growth and valuation of II-VI compound crystals under electrostatic field

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1. Effects of an Electrostatic Field on the Growth of CdS Crystals CdS crystals were grown from the vapor under an electrostatic field. When the potential of a central electrode was kept at a value less than minus several tens of volts crystals grew preferentially in the positive polar direction on the central electrode placed in the growth zone, but they grew preferentially in the negative polar direction when the potential was kept at a higher value than that value. These growth features are the same when crystals were grown on the basal plane of a CdS substrate fixed on the central electrode. CdS crystals growing on a central electrode or on a CdS substrate under alternating electric field with various frequencies were found to grow preferentially in the -c direction, except in the growth at 60Hz. The effect of electric field on the polarity of the grown crystals is attributed to accelerate deposition of Cd^+ ions onto the growing polar surface.2. Effects of an Electrostatic Field on the Growth of CuCl Crystals Three-Dimensional CuCl single crystals were observed among the crystals which have rotation twins. Crystals have branches growing in the <100> direction with four {111} facets at their top. CuCl crystals were also grown under an electrostatic field. However, it seems that the field affected only to suppress the growth of large crystals.3. PREPARATION OF WHISKERS AND SPRING-LIKE FIBERS OF Si_3N_4 Well-formed whiskers and regularly coiled spring-like fibers of Si_3N_4 have been obtained from a gas mixture of Si_2Cl_6, NH_3 and H_2 on a quartz or graphite substrate on which metal impurity was painted. The whiskers were alpha-Si_3N_4 accompanied by a small amount of beta-Si_3N_4, but the spring-like fibers were amorphous Si_3N_4. The most effective impurity for the growth of the whiskers was nickel for the quartz substrate and iron for the graphite.