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Anomalous K-Point Phonons in Noble Metal/Graphene Heterostructure Activated by Localized Surface Plasmon Resonance
ACS Nano ( IF 15.8 ) Pub Date : 2018-12-05 00:00:00 , DOI: 10.1021/acsnano.8b07761 Un Jeong Kim 1 , Jun Suk Kim 2, 3 , Noejung Park 4 , Sanghyub Lee 2, 3 , Ukjae Lee 5 , Yeonsang Park 1 , Jinbong Seok 2, 3 , Sungwoo Hwang 6 , Hyungbin Son 5 , Young Hee Lee 2, 3
ACS Nano ( IF 15.8 ) Pub Date : 2018-12-05 00:00:00 , DOI: 10.1021/acsnano.8b07761 Un Jeong Kim 1 , Jun Suk Kim 2, 3 , Noejung Park 4 , Sanghyub Lee 2, 3 , Ukjae Lee 5 , Yeonsang Park 1 , Jinbong Seok 2, 3 , Sungwoo Hwang 6 , Hyungbin Son 5 , Young Hee Lee 2, 3
Affiliation
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The metal/graphene interface has been one of the most important research topics with regard to charge screening, charge transfer, contact resistance, and solar cells. Chemical bond formation of metal and graphene can be deduced from the defect induced D-band and its second-order mode, 2D band, measured by Raman spectroscopy, as a simple and nondestructive method. However, a phonon mode located at ∼1350 cm–1, which is normally known as the defect-induced D-band, is intriguing for graphene deposited with noble metals (Ag, Au, and Cu). We observe anomalous K-point phonons in nonreactive noble metal/graphene heterostructures. The intensity ratio of the midfrequency mode at ∼1350 cm–1 over G-band (∼1590 cm–1) exhibits nonlinear but resonant behavior with the excitation laser wavelength, and more importantly, the phonon frequency–laser energy dispersion is ∼10–17 cm–1 eV–1, which is much less than the conventional range. These phonon modes of graphene at nonzero phonon wave vector (q ≠ 0) around K points are activated by localized surface plasmon resonance and not by the defects due to chemical bond formation of metal/graphene. This hypothesis is supported by density functional theory (DFT) calculations for noble metals and Cr along with the measured contact resistances.
中文翻译：
局部表面等离子体共振激活贵金属/石墨烯异质结构中的异常K点声子
在电荷屏蔽，电荷转移，接触电阻和太阳能电池方面，金属/石墨烯界面一直是最重要的研究主题之一。金属和石墨烯的化学键形成可以通过拉曼光谱法测量的，由缺陷诱发的D带及其二阶模式2D带推导得出，这是一种简单且无损的方法。然而，位于〜1350 cm –1处的声子模式（通常称为缺陷诱发的D带）吸引了沉积有贵金属（Ag，Au和Cu）的石墨烯。我们观察到非反应性贵金属/石墨烯异质结构中的异常K点声子。G波段（〜1590 cm –1）在〜1350 cm –1处的中频模式的强度比）在激发激光波长下表现出非线性但共振的行为，更重要的是，声子频率-激光能量色散约为10-17 cm -1 eV -1，远小于常规范围。在K点附近非零声子波矢量（q ≠0）处的这些石墨烯声子模式是通过局部表面等离振子共振而不是通过金属/石墨烯的化学键形成所引起的缺陷来激活的。该假设得到了贵金属和Cr的密度泛函理论（DFT）计算以及所测得的接触电阻的支持。
更新日期：2018-12-05
中文翻译：
局部表面等离子体共振激活贵金属/石墨烯异质结构中的异常K点声子
在电荷屏蔽，电荷转移，接触电阻和太阳能电池方面，金属/石墨烯界面一直是最重要的研究主题之一。金属和石墨烯的化学键形成可以通过拉曼光谱法测量的，由缺陷诱发的D带及其二阶模式2D带推导得出，这是一种简单且无损的方法。然而，位于〜1350 cm –1处的声子模式（通常称为缺陷诱发的D带）吸引了沉积有贵金属（Ag，Au和Cu）的石墨烯。我们观察到非反应性贵金属/石墨烯异质结构中的异常K点声子。G波段（〜1590 cm –1）在〜1350 cm –1处的中频模式的强度比）在激发激光波长下表现出非线性但共振的行为，更重要的是，声子频率-激光能量色散约为10-17 cm -1 eV -1，远小于常规范围。在K点附近非零声子波矢量（q ≠0）处的这些石墨烯声子模式是通过局部表面等离振子共振而不是通过金属/石墨烯的化学键形成所引起的缺陷来激活的。该假设得到了贵金属和Cr的密度泛函理论（DFT）计算以及所测得的接触电阻的支持。
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