Raman Excitation Profile of the G-band Enhancement in Twisted Bilayer Graphene
Raman Excitation Profile of the G-band Enhancement in Twisted Bilayer Graphene
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DOI：
10.1007/s13538-017-0526-8
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发表时间：
2017-12-01
影响因子：
1.6
通讯作者：
Pimenta, M. A.
中科院分区：
文献类型：
--
作者：
Eliel, G. S. N.;Ribeiro, H. B.;Pimenta, M. A.
在可见光范围内，利用多种不同的激光谱线对具有不同扭转角度的扭曲双层石墨烯（TBG）样品进行了共振拉曼研究。采用CVD技术制备样品，并将样品转移到Si/SiO2衬底上。实验得到了一组不同TBG薄片的g带强度大幅增强的拉曼激发谱，并利用拉曼强度的理论表达式对谱进行了分析，从而得到了莫尔产生的van Hove奇点的能量、模式和拉曼过程激发态的寿命。我们的结果显示了van Hove奇点的实验能量和计算能量之间的良好一致性，并表明光激发载流子的寿命不显著依赖于中间角范围内的扭转角（oee积分在10（ay）和15（ay）之间）。我们观察到共振窗的宽度（约250 meV）比碳纳米管的拉曼模式的REP大得多，这也被范霍夫奇点的共振增强了。
A resonant Raman study of twisted bilayer graphene (TBG) samples with different twisting angles using many different laser lines in the visible range is presented. The samples were fabricated by CVD technique and transferred to Si/SiO2 substrates. The Raman excitation profiles of the huge enhancement of the G-band intensity for a group of different TBG flakes were obtained experimentally, and the analysis of the profiles using a theoretical expression for the Raman intensities allowed us to obtain the energies of the van Hove singularities generated by the Moir, patterns and the lifetimes of the excited state of the Raman process. Our results exhibit a good agreement between experimental and calculated energies for van Hove singularities and show that the lifetime of photoexcited carrier does not depend significantly on the twisting angle in the range intermediate angles (oee integral between 10(ay) and 15(ay)). We observed that the width of the resonance window (I" ae 250 meV) is much larger than the REP of the Raman modes of carbon nanotubes, which are also enhanced by resonances with van Hove singularities.