Kinoshita Kyoichi, Ogata Yasuyuki, Adachi Satoshi, Yoda Shinichi, Tsuru Tetsuya, Miyata Hiroaki, Muramatsu Yuji
Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba, Ibakari, 305-8505 Japan.
Ann N Y Acad Sci. 2006 Sep;1077:161-71. doi: 10.1196/annals.1362.057.
The influence of convection in a melt on the crystallinity of the TLZ-grown In(0.3)Ga(0.7)As crystals has been investigated by growing crystals with various shapes and dimensions on the ground. No single crystals have been grown when the crystal diameter was 10 mm, but we were successful in growing single crystals by reducing crystal diameter to 2 mm. These results suggested the importance of suppressing convection in the melt during alloy crystal growth because constitutional supercooling tends to occur at the freezing interface or ahead of the interface by the segregation effect. Large area is required for substrate use in various applications. This requirement can be fulfilled by the crystal growth in microgravity because density difference-induced convection is suppressed in microgravity. Another means for suppressing convection without deteriorating area is plate-shape crystal growth with reduced thickness. The latter can be applied on the ground and we succeeded in growing single crystals of plate-shaped In(0.3)Ga(0.7)As by the traveling liquidus zone (TLZ) method. Dimensions of obtained single crystals were 10 mm in width and 2 mm in thickness and lengths ranged from 20 to 40 mm. Compositional uniformity was good and 0.3 +/- 0.02 in InAs mole fraction was achieved.
通过在地面上生长各种形状和尺寸的晶体，研究了熔体中的对流对提拉法生长的In(0.3)Ga(0.7)As晶体结晶度的影响。当晶体直径为10毫米时，未生长出单晶，但通过将晶体直径减小到2毫米，我们成功地生长出了单晶。这些结果表明，在合金晶体生长过程中抑制熔体中的对流很重要，因为由于偏析效应，成分过冷往往会在凝固界面或界面之前发生。在各种应用中，衬底使用需要大面积。由于在微重力环境中密度差引起的对流受到抑制，因此可以通过微重力环境中的晶体生长来满足这一要求。另一种在不降低面积的情况下抑制对流的方法是生长厚度减小的板状晶体。后者可以在地面上应用，我们通过移动液相区（TLZ）法成功地生长出了板状In(0.3)Ga(0.7)As单晶。获得的单晶尺寸为宽度10毫米、厚度2毫米，长度范围为20至40毫米。成分均匀性良好，InAs摩尔分数达到0.3±0.02。
