Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea.
Phys Rev Lett. 2010 Sep 17;105(12):127403. doi: 10.1103/PhysRevLett.105.127403. Epub 2010 Sep 15.
We report substantially enhanced photoluminescence (PL) from hybrid structures of graphene/ZnO films at a band gap energy of ZnO (∼3.3 eV/376 nm). Despite the well-known constant optical conductivity of graphene in the visible-frequency regime, its abnormally strong absorption in the violet-frequency region has recently been reported. In this Letter, we demonstrate that the resonant excitation of graphene plasmon is responsible for such absorption and eventually contributes to enhanced photoemission from structures of graphene/ZnO films when the corrugation of the ZnO surface modulates photons emitted from ZnO to fulfill the dispersion relation of graphene plasmon. These arguments are strongly supported by PL enhancements depending on the spacer thickness, measurement temperature, and annealing temperature, and the micro-PL mapping images obtained from separate graphene layers on ZnO films.
我们报告了在 ZnO（约 3.3 eV/376 nm）带隙能量的石墨烯/ZnO 薄膜的混合结构中，光致发光（PL）得到了极大的增强。尽管众所周知石墨烯在可见光频率范围内具有恒定的光学电导率，但最近有报道称其在紫光频率区域的吸收异常强烈。在这封信件中，我们证明了石墨烯等离子体的共振激发是导致这种吸收的原因，并且当 ZnO 表面的波纹调制从 ZnO 发射的光子以满足石墨烯等离子体的色散关系时，最终有助于增强石墨烯/ZnO 薄膜结构的光发射。这些论点得到了 PL 增强的强烈支持，这些增强取决于间隔层厚度、测量温度和退火温度，以及从 ZnO 薄膜上的单独石墨烯层获得的微 PL 映射图像。
