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采用熔体法生长Ⅱ-Ⅵ族碲化物体单晶时,不同的生长条件及热经历过程会导致生长态晶体材料中,占主导的点缺陷类型存在较大的差异,进而影响了晶体的物理性能及器件的使用。低温光致发光(PL)谱作为一种无损检测方法,可以用于研究不同条件下生长的Ⅱ-Ⅵ族碲化物体单晶中的点缺陷和杂质的能级状态。对比富Te条件下生长的未掺杂ZnTe和CdTe晶体在8.6 K下的PL谱可以发现,电阻率较低的p型ZnTe晶体,其PL谱中,电子到中性受主复合发光峰(e,A~0)强度高于施主-受主对复合发光峰(DAP),而高电阻率阻n型CdTe晶体则刚好相反,这可能是由于生长速率及降温过程的热经历不同导致占主导的本征点缺陷类型不同造成的。按化学计量比生长的未掺杂CdZnTe晶体,其PL谱中自由激子发光峰(D~0,X)占主导,而(e,A~0)峰强度高于DAP峰,变温PL谱测试表明当温度高于15 K时,(e,A~0)峰与DAP峰逐渐叠加在一起。In掺杂导致在富Te条件下生长的CdZnTe晶体的PL谱中产生明显的A中心复合发光峰,与导带的能量差约为0.15 eV,主要与In补偿Cd空位形成的复合体[In_(Cd)~+V_(Cd)~(2-)]~-有关,且其强度与In掺杂元素的含量成正比。
When using the melt method to grow single crystal of Ⅱ-Ⅵ group telluride, the different growth conditions and thermal history will lead to the big difference in dominant type of point defects in the grown crystal, which will affect the crystal physics Performance and device usage. As a non-destructive method, low-temperature photoluminescence (PL) spectroscopy can be used to study the state of point defects and impurity states of Ⅱ-Ⅵ group telluride single crystals grown under different conditions. Comparing the PL spectra of undoped ZnTe and CdTe crystals grown under Te-rich conditions at 8.6 K, it can be found that in the PL spectra of the p-type ZnTe crystals with lower resistivity, the electron to neutral acceptor recombination peak (e , A ~ 0) is higher than that of donor-acceptor vs. compound emission peak (DAP), whereas the high resistance resistive n-type CdTe crystal is just the opposite, which may be due to the different growth rate and thermal history of cooling process Eigenvalue defects caused by different types. The undoped CdZnTe crystals grown in stoichiometric ratio dominated the free exciton luminescence peak (D ~ 0, X) in the PL spectrum, while the peak intensity of (e, A ~ 0) was higher than that of DAP peak. It shows that when the temperature is higher than 15 K, the peak of (e, A ~ 0) gradually overlaps with the peak of DAP. The In doping results in the obvious A center recombination luminescence peak in the PL spectrum of CdZnTe crystal grown under Te-rich condition. The energy difference from the conduction band is about 0.15 eV, which is mainly in the complex of In compensation Cd) ~ + V Cd ~ (2 -)] ~ -, and its intensity is proportional to the content of In doping elements.