Cadmium chloride assisted re-crystallisation of CdTe: The effect on the CdS window layer
Cadmium chloride assisted re-crystallisation of CdTe: The effect on the CdS window layer
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DOI：
10.1557/opl.2015.177
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
A. Abbas;P. Kamiński;G. West;K. Barth;W. Sampath;J. Bowers;J. Walls
中科院分区：
文献类型：
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作者：
A. Abbas;P. Kamiński;G. West;K. Barth;W. Sampath;J. Bowers;J. Walls
©2015材料研究学会。氯化镉退火处理是制备高效薄膜碲化镉太阳能电池的重要步骤。在以前的工作中，我们已经表明，处理的主要效果是从沉积材料中去除高密度的层错。利用密度泛函理论表明，一些高能量层错是空穴圈闭。去除这些缺陷可显著提高电池效率。本文主要研究了活化处理对下伏n型硫化镉层的影响。一系列的技术已经被用来观察微观结构的变化，以及化学和晶体学的变化作为处理参数的函数。还进行了将设备性能与电池的微观结构特性联系起来的电气测试。使用的技术包括用于亚颗粒分析的高分辨率透射电子显微镜（HRTEM），用于化学分析的EDX和用于成分深度分析的XPS和SIMS。通过研究增加处理时间和温度的影响，我们将表明，硫化镉层耗尽到完全溶解到吸收层。我们还将证明氯在硫化镉中渗透和修饰晶界。此外，我们将证明氯在异质结处积聚，并在碲化镉/硫化镉界面处的空隙中富集。这些影响的综合会损害太阳能电池的电气性能。
© 2015 Materials Research Society. The cadmium chloride annealing treatment is an essential step in the manufacture of efficient thin film CdTe solar cells. In previous work we have shown that the primary effect of the treatment is to remove high densities of stacking faults from the as-deposited material. Use of density functional theory has shown that some of the higher energy stacking faults are hole traps. Removal of these defects dramatically improves cell efficiency. In this study we focus on the effect of the activation treatment on the underlying n-type cadmium sulphide layer. A range of techniques has been used to observe the changes to the microstructure as well as the chemical and crystallographic changes as a function of treatment parameters. Electrical tests that link the device performance with the micro-structural properties of the cells have also been undertaken. Techniques used include High Resolution Transmission Electron Microscopy (HRTEM) for subgrain analysis, EDX for chemical analysis and XPS and SIMS for composition-depth profiling. By studying the effect of increasing the treatment time and temperature, we will show that the cadmium sulphide layer depletes to the point of complete dissolution into the absorber layer. We will also show that chlorine penetrates and decorates the grain boundaries in the cadmium sulphide. In addition we will show that chlorine builds up at the heterojunction and concentrates in voids at the cadmium telluride/cadmium sulphide interface. A combination of these effects damages the electrical performance of the solar cell.