标题： 在氮化镓纳米线上的石墨烯增强的拉曼散射和弱局域化 显示英文标题

标题： Enhanced Raman scattering and weak localization in graphene deposited on GaN nanowires

摘要： 研究了沉积在GaN纳米线上的石墨烯的光学和电学性质受纳米线的影响，使用了拉曼光谱和微波诱导的电子输运方法。 发现与纳米线的相互作用引起了光谱变化以及拉曼散射强度的显著增强。 令人惊讶的是，缺陷引起的D'过程的增强最小（约30倍），而2D跃迁的强度增加最高（超过50倍）。 观察到的G带和2D带的能量位移使得能够确定由GaN纳米线引起的载流子浓度波动。 比较拉曼散射的空间强度图和使用扫描电子显微镜获得的图像得出结论，垂直对齐的GaN纳米线引起均匀应变、石墨烯中载流子浓度的显著空间调制以及由与纳米线相互作用产生的缺陷的意外均匀分布。 D峰和D'峰强度比的分析表明，与纳米线的相互作用也改变了不同类型的缺陷的散射概率。 拉曼研究与通过微波诱导的无接触电子输运测量的弱局域化效应相关。 弱局域化信号的温度依赖性显示电子-电子散射是主要的退相干机制，此外还有温度无关的散射减少了相干长度。 我们将此归因于石墨烯中的电子与由于GaN的自发极化和压电极化而在纳米线顶部存在的电荷之间的相互作用。 因此，纳米线起到天线的作用，并产生增强的近场，这可以解释观察到的拉曼散射强度的显著增强。 显示英文摘要

摘要： The influence of GaN nanowires on the optical and electrical properties of graphene deposited on them was studied using Raman spectroscopy and microwave induced electron transport method. It was found that interaction with the nanowires induces spectral changes as well as large enhancement of Raman scattering intensity. Surprisingly, the smallest enhancement (about 30-fold) was observed for the defect induced D' process and the highest intensity increase (over 50-fold) was found for the 2D transition. The observed energy shifts of the G and 2D bands allowed to determine carrier concentration fluctuations induced by GaN nanowires. Comparison of Raman scattering spatial intensity maps and the images obtained using scanning electron microscope led to conclusion that vertically aligned GaN nanowires induce a homogenous strain, substantial spatial modulation of carrier concentration in graphene and unexpected homogenous distribution of defects created by interaction with nanowires. The analysis of the D and D' peak intensity ratio showed that interaction with nanowires also changes the probability of scattering on different types of defects. The Raman studies were correlated with weak localization effect measured using microwave induced contactless electron transport. Temperature dependence of weak localization signal showed electron-electron scattering as a main decoherence mechanism with additional, temperature independent scattering reducing coherence length. We attributed it to the interaction of electrons in graphene with charges present on the top of nanowires due to spontaneous and piezoelectric polarization of GaN. Thus, nanowires act as antennas and generate enhanced near field which can explain the observed large enhancement of Raman scattering intensity.