Faculty of Nanotechnology and Advanced Materials, HMC, and Graphene Research Institute, Sejong University, Seoul, Korea.
Nanotechnology. 2012 Jul 20;23(28):285705. doi: 10.1088/0957-4484/23/28/285705. Epub 2012 Jun 25.
The influence of grain boundaries and mechanical deformations in graphene film on the electric charge transport is investigated at nanoscale with conductive atomic force microscopy. Large area monolayer graphene samples were prepared by the chemical vapor deposition technique. Field emission scanning electron microscopy confirmed the formation of grain boundaries and the presence of wrinkles. The presence of the D-band in the Raman spectrum also indicated the existence of sharp defects such as grain boundaries. Extremely low conductivity was found at the grain boundaries and the wrinkled surface was also more resistive in comparison to the plain graphene surface. Many samples were experimented with to justify our findings by selecting different areas on the graphene surface. Uniform conductivity was found on grain boundary and wrinkle free graphene surfaces. We made channels of varied lengths by local anodic oxidation to confine the charge carrier to the smallest dimensions to better confirm the alteration in current due to grain boundaries and wrinkles. The experimental findings are discussed with reference to the implementation of graphene as transparent conductive electrode.
采用原子力显微镜在纳米尺度上研究了石墨烯薄膜中的晶界和机械变形对电荷输运的影响。采用化学气相沉积技术制备了大面积单层石墨烯样品。场发射扫描电子显微镜证实了晶界的形成和褶皱的存在。拉曼光谱中 D 带的存在也表明存在尖锐的缺陷，如晶界。在晶界处发现了极低的电导率，与平整的石墨烯表面相比，褶皱表面的电阻也更高。通过选择石墨烯表面的不同区域，对多个样本进行了实验，以验证我们的发现。在晶界和无褶皱的石墨烯表面上发现了均匀的导电性。通过局部阳极氧化制作了不同长度的通道，将载流子限制在最小尺寸，以更好地确认由于晶界和褶皱引起的电流变化。实验结果结合了将石墨烯用作透明导电电极的应用进行了讨论。
