Department of Applied Chemistry, Kyung Hee University, Yongin, Gyeonggi 446-701, Korea.
Nano Lett. 2010 Dec 8;10(12):4944-51. doi: 10.1021/nl1029607. Epub 2010 Nov 11.
Using micro-Raman spectroscopy and scanning tunneling microscopy, we study the relationship between structural distortion and electrical hole doping of graphene on a silicon dioxide substrate. The observed upshift of the Raman G band represents charge doping and not compressive strain. Two independent factors control the doping: (1) the degree of graphene coupling to the substrate and (2) exposure to oxygen and moisture. Thermal annealing induces a pronounced structural distortion due to close coupling to SiO2 and activates the ability of diatomic oxygen to accept charge from graphene. Gas flow experiments show that dry oxygen reversibly dopes graphene; doping becomes stronger and more irreversible in the presence of moisture and over long periods of time. We propose that oxygen molecular anions are stabilized by water solvation and electrostatic binding to the silicon dioxide surface.
我们使用微拉曼光谱和扫描隧道显微镜研究了二氧化硅衬底上石墨烯的结构变形和电空穴掺杂之间的关系。观察到的拉曼 G 带的上移代表了电荷掺杂，而不是压缩应变。两个独立的因素控制着掺杂：（1）石墨烯与衬底的耦合程度，以及（2）暴露于氧气和水分。热退火由于与 SiO2 的紧密耦合而引起明显的结构变形，并激活了双原子氧从石墨烯接受电荷的能力。气流实验表明，干燥氧气可可逆地掺杂石墨烯；在存在水分和长时间的情况下，掺杂变得更强且更不可逆。我们提出，氧分子阴离子通过水的溶剂化和与二氧化硅表面的静电结合而稳定。
