摘要
我们用红外透射光谱和X射线双晶衍射等，研究了退火对CdZnTe晶体质量的影响．结果表明，在Cd气氛中，700℃，退火5小时以上，能大量地去除晶片中的Te沉淀，提高其红外透射比；同时，退火也导致了晶片表面的损伤，损伤层为50～130μm．表面结构损伤的原因是，（1）Cd气氛中退火，CdZnTe晶体表面的Zn损失；（2）退火过程中，吸附在沉淀物周围的杂质，尤其是快扩散杂质，将随着沉淀相的消失而迁移到晶体的表面，从而破坏了表面的晶体结构．退火后，磨去损伤层，可将聚集在表面的这些杂质除去，更有利于外延生长或器件制备．
The Room temperature infrared transmission spectra, infrared microscope and X-ray double-crystal rocking curve measurement were used to characterize the annealing effect of CdZnTe crystal wafers. Cd-annealing of Bridgman grown CdZnTe wafers for 5h or longer time at 700℃ enhances the IR transmittance of the wafer up to 64% and decreases Te precipitate density. The high IR transmittance obtained is attributed to annihilation of Cd vacancies or elimination of Te precipitates during annealing in Cd vapor. It is also found that Cd anneal degrades the CdZnTe crystalline quality. The damage depth is 50~130μm. The two mechanism of crystalline quality damage for an annealing in Cd vapor are possible (i) depletion of Zn from CdZnTe surface, and (ii) impurities released from the Te precipitates resulted in regrowth of CdZnTe give rise to imperfect crystallinity. However,the impuries released from the Te precipitates to CdZnTe wafer surface during Cd-annealling can be cleaned by removing the damaged surface of CdZnTe wafers, and therefore the CdZnTe wafers as substrates are more beneficial to growing Hg1-xCdxTe epilayers.
