arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1102.4543cond-mat.mtrl-sci
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Au(111)衬底对石墨烯的掺杂:局域密度近似和半经验范德华方法的计算策略

Doping of graphene by a Au(111) substrate: Calculation strategy within the local density approximation and a semiempirical van der Waals approach

J. Slawinska, P. Dabrowski, I. Zasada

摘要:

我们采用局域密度近似和Grimme提出的半经验van der Waals方法(称为DFT-D2方法)对吸附在Au(111)表面的石墨烯进行了密度泛函研究。物理吸附在金属上的石墨烯在能带结构中保持了线性色散,但系统的费米能级相对于锥形点发生了位移,这导致了掺杂效应。我们表明,掺杂的类型和量不仅取决于在计算中使用的交换相关功能的选择,但也对超晶胞几何模型的物理系统。我们分析了金的面内晶胞参数和层间距等因素对费米能级移动的影响,发现这些参数的微小变化都可能导致p型掺杂向n型掺杂的转变。我们选择了一组合理的模型参数,得到了石墨烯在清洁的Au(111)表面上要么是未掺杂的,要么最多是轻微的p型掺杂,这似乎与实验结果一致。另一方面,衬底晶格的改性可以诱导高达0.30-0.40 eV的更大掺杂,这取决于石墨烯-金属吸附距离。石墨烯-金界面对结构参数的敏感性可以允许调节样品之间的掺杂,这可能导致石墨烯基电子器件中的可能应用。我们相信,本文的结论对基于周期DFT的其他研究也是有用的。

英文摘要:

We have performed a density functional study of graphene adsorbed on Au(111) surface using both a local density approximation and a semiempirical van der Waals approach proposed by Grimme, known as the DFT-D2 method. Graphene physisorbed on metal has the linear dispersion preserved in the band-structure, but the Fermi level of the system is shifted with respect to the conical points which results in a doping effect. We show that the type and amount of doping depends not only on the choice of the exchange-correlation functional used in the calculations, but also on the supercell geometry that models the physical system. We analyzed how the factors such as the in-plane cell parameter and interlayer spacing in gold influence the Fermi level shift and we found that even a small variation in these parameters may cause a transition from p-type to n-type doping. We have selected a reasonable set of model parameters and obtained that graphene is either undoped or at most slightly p-type doped on the clean Au(111) surface, which seems to be in line with experimental findings. On the other hand, modifications of the substrate lattice may induce larger doping up to 0.30-0.40 eV depending on the graphene-metal adsorption distance. The sensitivity of the graphene-gold interface to the structural parameters may allow to tune doping across the samples which could lead to possible applications in graphene-based electronic devices. We believe that the present remarks can be also useful for other studies based on the periodic DFT.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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