HgCdTe晶体ACRT-B法生长过程的分凝特性研究

Solute Redistribution during ACRT-B Growth of HgCdTe

在定量估算的基础上，明确了 Ｈｇ１－ｘＣｄｘＴｅ晶体ＡＣ－ＲＴ一Ｂ法生长过程轴向溶质再分配的简化条件，导出了计算公式。以 ＨｇＴｅ－ＣｄＴｅ伪二元相图为基础进行的计算表明，按照远红外探测器要求的成分配料（Ｘ０＝０．２２），仅在晶锭的某一部分可获得符合成分容差的晶体。而采用其它相近的成分配比也能获得符合成分要求的晶体。采用ｘ０值更小的配料成分获得的满足成分要求的晶段更长，并且位于结晶质量较高的晶锭前段。

Based on some quantitative evaluations on the solute partition at growth interface, diffusion in the solid and the liquid, a mathematical model is deduced for the calculation of the solute redistribution during ACRT-B growth of Hgl-xCdxTe crystal. The results reveal the followings : (1) In Hgl-x.CdxTe crystal grown from the melt with the composition of Hg0. 78 Cd0. 22 Te (the most popular infrared detector material) by ACRT-B method, Cd content is much higher than the average value in the initial region and reduces along the growth direction to a very lower value in the final region because of solute redistribution. Only a part of the crystal fit the required composition with the acceptable error. (2) Hg0. 78Cd0. Te crystal with a certain composition error also exists in the ingot grown from Hg1-x.Cdx.Te melt with other average compositions, i. e. x0 value. The calculated solute distributions in Hgl-x.Cdx.Te ingots grown from the melts with four different xo values were calculated. It is shown that, the length of the region with acceptable composition increases with decreasing in x0 value until x0 reaches a certain limit. Meanwhile, the region moves toward the initial region. (3) To grown Hg1-x .CdxTe crystal with a certain composition,such as x= 0. 22,it is preferable to use the melt with a lower average Cd content, so that the region with the acceptable composition will be longer and located in the early region where the crystallization quality is better.