Mg _x Zn _{1− x} O (MZO) is a promising window material for high-efficiency CdTe thin film solar cell fabrication. However, the performance of MZO-based CdTe solar cell exhibits high sensitivity to the heat treatment of MZO during device fabrication process. In this article, the chemical, microstructural and electrical instability of MZO films and their effect on device performance of CdTe thin film solar cell was studied. It is found that during the high-temperature vacuum treatment (400°C−600°C), the atomic element losses in the MZO films led to high oxygen-vacancy concentration and formation of an Mg-rich surface layer. The high-temperature treated MZO films exhibited rough surface morphology, high electronic conductivity, and low electron affinity. The rough MZO surface induced formation of trap states with high concentration in the CdTe absorber and decreased open-circuit voltage for the solar cell. The MZO conductivity and the surface electron affinity affect the carrier transport in the solar cells. This work demonstrates that the heat treatment process of the MZO window layer significantly affects the performance and reproducibility of CdTe solar cell fabrication.

中文翻译：

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CdTe薄膜太阳能电池中Mg _x Zn _1-x O的化学和电不稳定性

镁 _X 锌 _{1− X} O (MZO) 是一种用于高效碲化镉薄膜太阳能电池制造的有前途的窗口材料。然而，基于 MZO 的 CdTe 太阳能电池的性能在器件制造过程中对 MZO 的热处理表现出很高的敏感性。本文研究了 MZO 薄膜的化学、微观结构和电学不稳定性及其对 CdTe 薄膜太阳能电池器件性能的影响。发现在高温真空处理（400°C-600°C）期间，MZO 薄膜中的原子元素损失导致高氧空位浓度和富镁表面层的形成。高温处理的 MZO 薄膜表现出粗糙的表面形态、高电子电导率和低电子亲和力。粗糙的 MZO 表面会在 CdTe 吸收剂中诱导形成高浓度的陷阱态，并降低太阳能电池的开路电压。MZO 电导率和表面电子亲和力影响太阳能电池中的载流子传输。这项工作表明，MZO 窗口层的热处理工艺显着影响 CdTe 太阳能电池制造的性能和再现性。