Formation of the Cd2Te2O7 phase induced by chemical etching and its influence on the electrical properties of Au/CdTe contacts,CrystEngComm

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Formation of the Cd2Te2O7 phase induced by chemical etching and its influence on the electrical properties of Au/CdTe contacts
CrystEngComm ( IF 2.6 ) Pub Date : 2020-10-21 , DOI: 10.1039/d0ce01148g
Xiaokai Shi _{1,

2,

3,

4,

5} , Juanjuan Ma _{2,

3,

4,

6} , Lijian Zheng _{2,

3,

4,

6} , Xiuping Yue _{1,

2,

3,

4} , Lijun Liu _{4,

7,

8}

Affiliation

CdTe and related II–VI compound semiconductors have been widely utilized in the field of optoelectronic devices, detectors, solar cells and so on. As the surface treatment on the wafer involved in the device fabrication process has an important impact on its subsequent photoelectric performance, the investigations on the change in structures and properties of the wafer after different surface treatments, especially the formation of new phases at the surface, have important theoretical significance and practical application value. In this work, the surface morphology and microstructure of CdTe single crystal wafers after different chemical etching processes were investigated by atomic force microscopy (AFM), Raman spectroscopy and transmission electron microscopy (TEM). With the increase of etching time to 10 min, the surface gradually became smoother with a significantly reduced surface roughness from 61.4 nm to 30.5 nm. In addition, the I–V curves of Au/CdTe contact structure illustrate the optimized ohmic contact characteristics after chemical etching with the surface leakage current increasing from 4.723 × 10⁻¹⁰ A to 3.640 × 10⁻⁹ A when the etching time extends up to 10 min. TEM analysis on the chemical etched surface of CdTe confirms the formation of Cd₂Te₂O₇ phase with two variants. The d-spacing of (100)_CTO and twice that of {111}_CdTe being similar is the main reason for the existence of low lattice mismatch and formation of coherent interface between Cd₂Te₂O₇ and CdTe. Furthermore, the chemical etching process is also confirmed to remove the surface damage caused by mechanical polishing effectively by comparing the interface microstructures of Au/CdTe contacts without and after 10 min of chemical etching. The formation mechanism of Cd₂Te₂O₇ and the structure model of Au/CdTe interface are also proposed based on the TEM results.

中文翻译：

化学腐蚀引起的Cd2Te2O7相的形成及其对Au / CdTe触点电性能的影响

CdTe和相关的II-VI化合物半导体已在光电器件，探测器，太阳能电池等领域得到了广泛应用。由于涉及器件制造过程的晶圆表面处理对其后续的光电性能有重要影响，因此，对不同表面处理后晶圆结构和性能变化的研究，尤其是在表面形成新相的研究，具有重要的理论意义和实际应用价值。在这项工作中，通过原子力显微镜（AFM），拉曼光谱和透射电子显微镜（TEM）研究了不同化学刻蚀工艺后CdTe单晶晶片的表面形态和微观结构。随着蚀刻时间增加到10分钟，表面逐渐变得光滑，表面粗糙度从61.4 nm显着降低到30.5 nm。除此之外我- V的Au / CdTe的接触结构的曲线说明了从4.723×10增加与表面的泄漏电流的化学蚀刻后的优化欧姆接触特性^-10 A至3.640×10 ^-9当向上的蚀刻时间延长至10分钟A。对CdTe的化学蚀刻表面进行的TEM分析证实，形成了具有两种变体的Cd ₂ Te ₂ O ₇相。（100）_CTO的d间距和{111} _CdTe的d间距相似是造成低晶格失配和Cd ₂ Te ₂ O之间形成相干界面的主要原因₇和CdTe。此外，通过比较未经过化学刻蚀和经过10分钟刻蚀后的Au / CdTe触点的界面微观结构，还可以肯定地通过化学刻蚀工艺有效地消除了由机械抛光引起的表面损伤。根据TEM结果，提出了Cd₂ Te₂ O₇的形成机理和Au / CdTe界面的结构模型。

更新日期：2020-11-12

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