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采用传统Bridgman方法和加入acceleratedcruciblerotationtechnique的Bridgman(缩写为ACRT B)方法生长的Cd1 -xZnxTe(x=0 .0 4)晶体中存在有点缺陷、位错、杂质和Te沉淀等缺陷 .为了减少甚至消除这些缺陷 ,必须将生长后的CdZnTe晶片在Cd气氛下退火 .从Cd -Te和Cd0 .96 Zn0 .0 4Te的P T相图出发 ,详细讨论了CdZnTe晶体的气 固平衡条件 ,并以此为依据选择退火条件 ,对ACRT -B法生长的Cd0 .96 Zn0 .0 4Te晶体进行了退火实验研究 .实验结果表明 ,气氛中的Zn压在一定程度内高于平衡压力有利于晶体中多余Te向晶体表面扩散 ,即有利于消除Te沉淀 .但过高的Zn压会使晶体表面成分偏离原始的化学配比 .此时 ,晶体表面与气氛强烈的原子交换 ,将造成严重的表面损伤 ,形成一层结晶质量很差的表面层 .同时 ,Zn原子向晶内的扩散 ,抑制了退火过程中晶内杂质向晶体表面的扩散 .因此 ,在较低的Zn压下退火 (但仍处于气 固平衡范围内 ) ,能排除晶内杂质 .通过仔细研究不同条件下退火后晶片的结晶质量和断面成分分布 ,可以认为CdZnTe晶体的退火可分为去沉淀相退火、去杂质退火和均匀化退火几种 ,最佳的退火工艺应是多步骤、多阶段的组合退火工艺
The Cd1-xZnxTe (x = 0.04) crystals grown by the traditional Bridgman method and the Bridgman method (abbreviated as ACRT B) added to acceleratedcrucible rotation technique have some defects such as point defects, dislocations, impurities and Te precipitation.In order to reduce or even eliminate these The CdZnTe wafers must be annealed in the atmosphere of Cd.According to the PT phase diagram of Cd-Te and Cd0.96 Zn0.040Te, the gas-solid equilibrium conditions of CdZnTe crystals are discussed in detail and based on this, Annealing conditions, annealing of Cd0.96Zn0.040Te crystal grown by ACRT-B method was carried out.The experimental results show that the Zn pressure in the atmosphere is higher than the equilibrium pressure to a certain extent, which is beneficial to the excess Te in the crystal to the crystal surface Diffusion, that is conducive to the elimination of Te precipitation, but too high Zn pressure will make the crystal surface components deviate from the original chemical ratio.At this point, the crystal surface and strong atmosphere atomic exchange, will result in serious surface damage, the formation of a layer of crystallization Poor quality of the surface layer.At the same time, the diffusion of Zn atoms into the crystal, inhibit the diffusion of the intragranular impurities to the crystal surface during annealing.Therefore, annealing at a lower Zn pressure (but still In the gas-solid equilibrium range), can exclude impurities within the crystal.By careful study of the crystallization quality and cross-sectional composition distribution of the wafer after annealing under different conditions, it can be concluded that the annealing of CdZnTe crystals can be divided into precipitation-annealing, de-annealing and uniform Several kinds of annealing, the best annealing process should be multi-step, multi-stage combination annealing process