Grain and crystal texture properties of absorber layers in MOCVD-grown CdTe/CdS solar cells
Grain and crystal texture properties of absorber layers in MOCVD-grown CdTe/CdS solar cells
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DOI：
10.1088/0268-1242/21/6/009
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发表时间：
2006-06
影响因子：
1.9
通讯作者：
G. Zoppi;K. Durose;S. Irvine;V. Barrioz
中科院分区：
文献类型：
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作者：
G. Zoppi;K. Durose;S. Irvine;V. Barrioz
研究了350 °C下金属有机化学气相沉积（MOCVD）生长的CdTe/CdS/ITO/玻璃太阳能电池结构中4-13 μm厚CdTe吸收层的微结构。晶体织构，晶格参数和晶粒尺寸作为生长层的厚度的函数进行测量，并作为退火温度和退火时间的函数在氮气（N2）和氯化镉（CdCl 2）的环境。平均晶粒尺寸随厚度的变化为r（µm）= 0.050x − 0.10（4 < x < 12 µm），这种行为与500 °C下生长的近距离升华材料形成对比。在两种环境中的退火促进晶粒生长（其中瑞利晶粒尺寸分布函数和伯克-特恩布尔指数在440 °C下为n = 7，在400 °C下为n = 4），从[1 1 1]到[2 1 1]的生长中优选取向的发展，以及生长中压缩应力的释放。[2 1 1]择优取向的发展可能伴随晶粒生长的生长机制进行了描述。得出的结论是，在高于350 °C的温度下使用MOCVD生长将需要产生光伏应用所需的更大的晶粒尺寸。
The microstructure of 4–13 µm thick CdTe absorber layers in CdTe/CdS/ITO/glass solar cell structures grown by metal-organic chemical vapour deposition (MOCVD) at 350 °C has been studied. The crystalline texture, lattice parameter and grain size were measured as a function of thickness for the as-grown layers, and as a function of annealing temperature and time for annealing in both nitrogen (N2) and cadmium chloride (CdCl2) environments. The average grain sizes developed with thickness as r (µm) = 0.050x − 0.10 (4 < x < 12 µm), and this behaviour is contrasted with that for close-spaced sublimation material grown at 500 °C. Annealing in both ambients promoted grain growth (with Rayleigh grain size distribution functions and Burke–Turnbull exponents being n = 7 at 440 °C and ∼4 at 400 °C), a development of the grown-in preferred orientation from [1 1 1] to [2 1 1], and relief of the grown-in compressive stress. A growth mechanism by which development of the [2 1 1] preferred orientation may accompany grain growth is described. It is concluded that MOCVD growth at temperatures higher than 350 °C used here will be required to produce the larger grain sizes required for photovoltaic applications.