Energetics and Atomic Structures of Cu2Te Over layers on CdTe(111)
Energetics and Atomic Structures of Cu2Te Over layers on CdTe(111)
复制标题
CdTe(111) 层上 Cu2Te 的能量学和原子结构
DOI：
10.1021/jp511776e
复制
发表时间：
2015
影响因子：
3.7
通讯作者：
Zhang Zhenyu
中科院分区：
文献类型：
--
作者：
Choi Jin-Ho;Zhu Wenguang;Ho Kai-Ming;Wang Deliang;Zhang Zhenyu
尽管Cu2Te作为背接触材料被广泛应用于CdTe太阳能电池中，但Cu2Te/CdTe界面的确切原子结构仍不清楚。利用密度泛函理论中的第一性原理计算，基于我们最近确定的稳定的块体Cu2Te的层状结构，我们探索了CuTe(111)表面上Cu2Te覆盖层的可能结构。我们发现，尽管第一层外延覆盖层已经比块体Cu2Te更稳定，但由于与面内应变相关的巨大能量成本，无应变块状组态在能量上比各种外延组态更有利。热力学分析进一步证实，在典型的实验生长温度(∼700K)下，无应变块状界面结构仍然是稳定的。还发现范德华力在Cu2Te覆盖层的堆积过程中起着相当大的作用。这些发现将结合现有的和新的实验结果进行讨论，并可能刺激未来的系统实验。
Although Cu2Te is widely used as a back contact material in CdTe solar cells, the exact atomic structure of the Cu2Te/CdTe interface remains unclear. Using first-principles calculations within density functional theory, we search for possible structures of Cu2Te overlayers on CdTe(111) surfaces based on our recent theoretical determination of a stable layered structure of bulk Cu2Te. We discover that the unstrained bulklike configuration is energetically more favorable than various epitaxial configurations because of the significant energy costs associated with the in-plane strain, even though the first epitaxial overlayer is already more stable than bulk Cu2Te. Our thermodynamic analysis further confirms that the unstrained bulklike interface structure is still stable at typical experimental growth temperatures (∼700 K). It is also found that van der Waals forces play a considerable role in the stacking of the Cu2Te overlayers. These findings are discussed in connection with existing and new experimental results and will likely stimulate future systematic experiments.