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arXiv 2007.12272cond-mat.mtrl-scicond-mat.mes-hall
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石墨烯同位素超晶格的实空间拉曼光谱

Real Space Raman Spectroscopy of Graphene Isotope Superlattices

Eric Whiteway, Martin Lee, Michael Hilke

摘要:

报道了化学气相沉积法制备的12 C/13 C石墨烯同位素超晶格的拉曼光谱。在大的周期的拉曼光谱对应于批量12 C和13 C的贡献的总和。然而,在小的周期,我们观察到的混合12 C/13 C模式的拉曼过程,涉及两个声子,这导致在2D和2D'拉曼峰的三倍的形成。在实空间拉曼光谱的框架中可以很好地理解这种三倍,其中两个发射的声子来自超晶格的不同区域。混合峰的强度随着超晶格半周期接近光激发电子-空穴对的平均自由程而增加。通过在6和225 nm之间改变超晶格周期,我们可以直接测量光激发电子平均自由程,发现悬浮石墨烯为18 nm,SiO2衬底上石墨烯为7 nm。

英文摘要:

We report the Raman spectroscopy of 12C/13C graphene isotope superlattices synthesized by chemical vapour deposition. At large periods the Raman spectra corresponds to the sum of the bulk 12C and 13C contributions. However, at small periods we observe the formation of mixed 12C/13C modes for Raman processes that involve two phonons, which results in the tripling of the 2D and 2D' Raman peaks. This tripling can be well understood in the framework of real space Raman spectroscopy, where the two emitted phonons stem from different regions of the superlattice. The intensity of the mixed peak increases as the superlattice half period approaches the mean free path of the photo-excited electron-hole pairs. By varying the superlattice period between 6 and 225 nm we have a direct measure of the photo-excited electron mean free path, which was found to be 18 nm for suspended graphene and 7 nm for graphene on SiO2 substrates.

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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