科研之友
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摘要
By mechanical exfoliation, it is possible to deposit atomically thin mica flakes down to single-monolayer thickness on SiO(2)/Si wafers. The optical contrast of these mica flakes on top of a SiO(2)/Si substrate depends on their thickness, the illumination wavelength, and the SiO(2) substrate thickness, and can be quantitatively accounted for by a Fresnel-law-based model. The preparation of atomically thin insulating crystalline sheets will enable the fabrication of ultrathin, defect-free insulating substrates, dielectric barriers, or planar electron-tunneling junctions. Additionally, it is shown that few-layer graphene flakes can be deposited on top of a previously transferred mica flake. Our transfer method relies on viscoelastic stamps, as used for soft lithography. A Raman spectroscopy study shows that such an all-dry deposition technique yields cleaner and higher-quality flakes than conventional wet-transfer procedures based on lithographic resists.
- 出版日期2011-9-5
