Cd/Zn气氛退火过程中CdZnTe晶体内Te夹杂的迁移研究

Study on Te inclusions migration in CdZnTe single crystals during annealing under Cd/Zn vapor

通过红外透过成像研究了 Cd/Zn 气氛退火过程中 Cd0．9 Zn0．1 Te∶In 晶体内 Te 夹杂的密度及尺寸分布的演变.结果发现,Cd/Zn 气氛退火前,晶体中的 Te 夹杂密度分布比较均匀；退火后,晶体高温端近表面区域的 Te 夹杂密度较退火前提高了1个数量级,而晶体内部的 Te 夹杂密度则较退火前降低了1个数量级,且其密度沿温度梯度方向逐渐增加.退火前,晶体表面和内部的 Te 夹杂的直径主要分布在1~25μm；退火后,在晶体表面,直径＜45μm 的 Te 夹杂密度显著增大；而在晶体内部,直径＜5μm 和＞25μm的 Te 夹杂密度显著增大.导致这些现象的原因是退火过程中,Te 夹杂沿着温度梯度方向不断向晶体表面迁移,在迁移过程中尺寸相近的 Te 夹杂通过合并长大,尺寸相差较大的 Te 夹杂则以 Ostwald 熟化方式长大,并使小尺寸的 Te 夹杂更小.但由于熟化不充分,在 Ostwald 熟化长大过程中留下了很多尺寸＜5μm 的 Te 夹杂颗粒.

The variation of density and diameter of Te inclusions in indium-doped Cd0.9 Zn0.1 Te （CZT）single crys-tals during annealing under Cd/Zn vapor were studied via IR microscopy observation.The results indicated that the density of Te inclusions distributed homogeneously before annealing,while after annealing,the density of Te inclusions increased for about one order near the surface,but decreased for one order inside,and the density increased gradually along the direction of temperature gradient.The diameter of Te inclusions was mainly be-tween 1 μm and 25 μm before annealing,while those with the diameter ＆lt;45 μm near the wafer’s surface and those ＆lt;5 μm and ＆gt;25 μm inside increased notably after annealing.The reason for the above variation was de-termined by Te inclusions migration along the direction of temperature gradient.And during the migration,Te inclusions grew via incorporating with those with similar diameter and Ostwald ripening among those with com-paratively different diameter.But the ripening was not sufficient so that many smaller Te inclusions remained in the annealed samples.