Influence of Cd-rich Annealing on Position-dependent Conductivity Transition in Cd1-xZnxTe Crystal
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摘要: 在富Te生长条件下，通过垂直布里奇曼法制备的部分碲锌镉晶体内存在导电类型转变界面。采用富Te液相外延技术在含有导电类型转变界面的碲锌镉衬底上生长碲镉汞薄膜，制成的红外焦平面探测器响应图上存在明显的响应不均匀分界面。碲锌镉晶体的导电类型转变由缺陷类型的不同引起，为消除碲锌镉衬底的导电类型转变界面，提升碲镉汞红外焦平面的成像质量，对含有导电类型转变界面的碲锌镉晶体进行了Cd饱和气氛退火实验，研究了时间和温度等退火条件对晶体导电类型转变界面的影响，探讨了Cd间隙和Cd空位缺陷的形成机制，为晶体生长过程中的Cd空位缺陷抑制提出了解决思路。Abstract: In this study, Cd1-xZnxTe(x=0.04) crystals were grown using the Te-rich Vertical Bridgman(VB) method. A position-dependent conductivity transition was found in some of the as-grown Cd1-xZnxTe ingots, which caused significant nonuniformity in the Hg1-yCdyTe(MCT) focal plane array(FPA) response map. Cd-rich annealing experiments were performed on Cd1-xZnxTe ingots with position-dependent conductivity transition, and the relationships between the position-dependent conductivity transition and annealing conditions, including annealing time, temperature, and Cd partial pressure, were studied. Furthermore, by understanding the formation mechanism of Cd vacancies and Cd interstitials, we found that Cd vacancies can be reduced during Cd1-xZnxTe ingot growth.
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Key words:
- Cd1-xZnxTe /
- position-dependent conductivity transition /
- annealing /
- Cd reservoir
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图 1 含有导电类型转变界面的碲锌镉晶体退火前后结果
Figure 1. Results of Cd0.96Zn0.04Te crystal dealing with annealing method which leads to a position-dependent transition from p- to n-type conductivity
图 2 退火对碲锌镉晶体中的导电类型转变界面的影响
Figure 2. Influence of Cd-rich annealing on position-dependent conductivity transition in Cd1-xZnxTe
图 3 碲锌镉晶体在退火前和后，导电类型转变界面两侧的红外光谱
Figure 3. IR transmission of Cd1-xZnxTe, as-grown and post-annealed by Cd-rich condition
图 4 由生长在具有或者没有导电类型转变界面的碲锌镉衬底上的碲镉汞材料制成的红外焦平面响应图：(a) 有导电类型转变界面的情况；(b) 经退火消除导电类型转变界面的情况
Figure 4. Response map of IR FPA made of MCT grown on Cd1-xZnxTe substrates, with (a) or without (b) position-dependent conductivity transition
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