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

1. 静电场对CdS晶体生长的影响研究了静电场作用下CdS晶体的生长。当中心电极电位低于负几十伏特时，晶体在生长区内的中心电极上优先向正极方向生长，而当中心电极电位高于负几十伏特时，晶体优先向负极方向生长。当晶体生长在固定在中心电极上的CdS衬底的基面上时，这些生长特征是相同的。在不同频率的交变电场作用下，在中心电极或CdS衬底上生长的CdS晶体除了在60Hz下生长外，均优先向-c方向生长。电场对生长的晶体极性的影响是由于加速了Cd^+离子在生长的极性表面上的沉积。静电场对CuCl晶体生长的影响在具有旋转孪晶的晶体中观察到三维CuCl单晶。晶体的分枝生长在<100>方向，顶部有四个{111}刻面。CuCl晶体也在静电场下生长。然而，电场的作用似乎只抑制了大晶体的生长。在涂有金属杂质的石英或石墨衬底上，用Si_2Cl_6、NH_3和H_2混合气体制备了结构良好的Si_3N_4晶须和有规则卷曲的Si_3N_4弹簧状纤维。晶须为α -Si_3N_4并伴有少量的β -Si_3N_4，而弹簧状纤维为无定形Si_3N_4。对晶须生长最有效的杂质是镍（石英衬底）和铁（石墨衬底）。

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.