MATERIAL STRENGTH STUDY ON GROWTH OF HIGH QUALITY BULK SINGLE CRYSTALS FOR ELECTRONIC/OPTICAL DEVICES

1.利用Haasen-Sumino位错动力学模型，编制了计算硅、砷化镓和磷化铟单晶体直拉法生长过程中位错密度的计算机程序。以下是使用该计算机代码进行分析所获得的研究结果。(1)位错增殖速率按GaAs、InP和Si的顺序较快。即使在Si的情况下，位错密度也在几秒钟内达到稳态值，InP和GaAs的位错倍增速率分别快于100倍和1000倍。(2)InP和GaAs在稳定状态下具有比Si更大的位错密度。(3)对CZ生长过程的连续模拟给出了位错密度沿块体单晶直径沿着的W型分布，这在真实的块体单晶中观察到。这验证了计算机模拟.以下是关于以下关系的研究结果： 关于我们 LiNbO_3（LN）单晶生长过程中的热应力及其质量。(1)热应力在a轴拉伸中比在c轴拉伸中高。这验证了在a轴拉伸中比在c轴拉伸中更容易发生开裂的经验事实。(2)根据热应力分析，在a轴方向上生长的单晶在其内部具有比在c轴方向上生长的单晶更宽的低热应力区域。这意味着a轴提拉比c轴提拉得到质量更高的块状单晶。用X射线形貌图对单晶质量的检查揭示了在a轴提拉中生长的单晶的高质量，其具有比在c轴方向上生长的单晶更少的亚晶粒。结果表明，热应力分析的结果为高质量单晶的生长方法提供了有效的信息。(3)由于热应力导致的LN单晶的失效发生在解理面处，并且可以由垂直于解理面的张应力支配。破坏应力服从威布尔分布。少

1. A computer code was developed for for evaluating the dislocation density of Si, GaAs and InP bulk single crystals during the Czochralski growth using a dislocation kinetics model called the Haasen-Sumino model. The following are the research results obtained from the analyzes using this computer code. (1) The rate of dislocation multiplication is faster in the order of GaAs, InP and Si. Even in the case of Si, the dislocation density reaches a steady state value within a few seconds, and InP and GaAs have faster rate of dislocation multiplication by more than a hundred times and a thousand times, respectively. (2) InP and GaAs have larger dislocation density at a steady state than Si. (3) A continuous simulation for the CZ growth process gives a W-type distribution of dislocation density along a diameter of a bulk single crystal, which is observed in a real bulk single crystal. This verifies the computer simulation.2. The following are results of the research on the relation between … More the thermal stress during the growth of a LiNbO_3 (LN) single crystal and its quality. (1) Thermal stress is higher in the a-axis pulling than in the c-axis pulling. This verifies the empirical fact that cracking is easier to occur in the a-axis pulling than in the c-axis pulling. (2) According to the thermal stress analysis, a single crystal grown in the a-axis direction has a wider region of low thermal stress in its internal part than a single crystal grown in the c-axis direction. This implies that the a-axis pulling gives a bulk single crystal with higher quality than the c-axis pulling. The examination of the quality of single crystals with the x-ray topograph reveals high quality of a single crystal grown in the a-axis pulling which has fewer subgrains than a single crystal grown in the c-axis direction. It is shown that the results of the thermal stress analysis give effective information on the growth method of a single crystal with high quality. (3) Failure of a LN Single crystal due to thermal stress occurs at the cleavage planes and may be dominated by the tensile stress normal to the cleavage planes. The failure stress shows the Weibull distribution. Less