采用高压液封直拉法生长2英寸N型掺硫GaP单晶,通过浮舟技术控制直径.按照理论公式计算出掺杂量,采用范德堡法测试掺硫GaP单晶头部、中部和尾部的载流子浓度.分析了固液界面形状对载流子分布的影响,在平坦的固液界面下得到的单晶载流子分布更为均匀.探讨了浮舟控径单晶横向和纵向载流子分布及其影响因素.比较和讨论了浮舟控径和无舟计算机闭环控径单晶纵向载流子分布,表明采用浮舟控制及工艺,造成晶体生长过程中分凝系数及补偿度的变化,使得晶体纵向载流子浓度先降低后升高,提出了通过变速拉晶,可以改善单晶纵向载流子均匀性.讨论了浮舟质量对载流子分布的影响,采用质量较大的浮舟生长GaP单晶,其纵向载流子分布更均匀.
Two inches N-type sulfer-doped GaP single crystal was grown by high pressure LEC method,crystals diameter were controlled by floating coracle technique.The doping amount was calculated according to the theoretical formula, and the carrier concentration of the head, middle and tail of the sulfur-doped GaP single crystal were measured by the Vanderbilt method.The influence of the shape of the solid-liquid interface on the carrier distribution is analyzed.The flat solid-liquid interface has a more uniform carrier distribution in the crystal.The distribution of lateral and longitudinal carriers and their influencing factors on the coracle-controlled single crystal were analyzed.The longitudinal carrier distribution of the single crystal controlled by computer and the floating coracle is compared and discussed.It shows that the floating coracle control and process cause the change of the segregation coefficient and the compensation degree during the crystal growth, so that the longitudinal carrier concentration of the crystal first decreases and then rises.It is proposed that the single crystal longitudinal carrier uniformity can be improved by shifting crystal pulling.The influence of the weight of the coracle on the carrier distribution is discussed.The longitudinal carrier distribution is more uniform while using heavier coracle during GaP crystal growth.
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