arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1010.2772cond-mat.mtrl-sci
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BaCuChF(Ch=S,Se,Te)p型透明导体的缺陷物理

Defect physics of BaCuChF (Ch=S, Se, Te) p-type transparent conductors

A. Zakutayev, J. Tate, G. Schneider

摘要:

利用密度泛函理论计算、自洽热力学模拟和各种实验技术研究了BaCuChF中的本征点缺陷、缺陷复合物和氧杂质。无意的p型导电性BaCuChF的解释与过渡水平的价带中的铜空位的存在。这些受体类缺陷的部分补偿施主类硫族元素空位与过渡水平深的差距。硫族空位也导致实验观察到的子间隙光致发光,光吸收,和持久的光电导BaCuSF和BaCuSeF。在热力学平衡中,铜和硫族元素空位都具有低的形成能力,并且很可能在它们之间以及与氟化合物形成缺陷复合物。计算得到的BaCuChF的费米能级钉扎范围较窄,靠近价带最大值。这使得BaCuChF成为用于光电应用的合适的透明p型接触层,但阻碍了使用该材料制造透明薄膜晶体管的尝试。氧相关的缺陷不影响批量BaCuChF的性能,但表面氧化减少了自由空穴的平均自由程几乎一个数量级。

英文摘要:

Native point defects, defect complexes, and oxygen impurities in BaCuChF were studied using density functional theory calculations, self-consistent thermodynamic simulations, and various experimental techniques. Unintentional p-type conductivity in BaCuChF is explained by the presence of copper vacancies with transition levels in the valence band. These acceptor-like defects are partially compensated by donor-like chalcogen vacancies with transition levels deep in the gap. Chalcogen vacancies also cause the experimentally observed sub-gap photoluminescence, optical absorption, and persistent photoconductivity in BaCuSF and BaCuSeF. In thermodynamic equilibrium, both copper and chalcogen vacancies have low formation enthalpies and are likely to form defect complexes among themselves and with fluorine interstitials. The calculated Fermi level pinning range in BaCuChF is narrow and located close to the valence band maximum. It makes BaCuChF a suitable transparent p-type contact layer for optoelectronic applications, but hinders attempts to fabricate transparent thin film transistors using this material. Oxygen-related defects do not affect bulk BaCuChF properties, but surface oxidation decreases the mean free path of free holes by almost an order of magnitude.

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