本實驗主要研究內容為探究鐵電性薄膜對吸附於其表面上的石墨烯樣品能帶結構之調控。我們透過剝離石墨法使樣品吸附於鐵酸鉍薄膜表面上，並利用掃描式電子顯微鏡進行低層數石墨烯的找尋與定位，再進行拉曼光譜的測量與分析來確定各低層數石墨烯樣品之厚度，並從中挑選單層與雙層石墨烯樣品進行鐵電性基板對其影響之分析。透過掃描探針顯微術的應用，使我們可以直接利用外加偏壓於原子力顯微鏡之探針上，來對石墨烯樣品所覆蓋的鐵酸鉍基板進行自發極化方向之切換，並從光電子能譜學與拉曼光譜學的分析中得知，石墨烯的主要載子在經過外加偏壓的操作後將從電洞轉變為電子，並且其費米能級移動了0.2eV。

We demonstrate a ferroelectric manipulation of graphene doping level in the graphene-BiFeO3 (BFO) hybrid system. Here, the graphene sheets were prepared by mechanical exfoliation of small mesas of highly oriented pyrolytic graphite (HOPG) and transferred on the BFO substrate. After locating monolayer-graphene sheets through scanning electron microscope (SEM) and Raman spectroscopy, a spatially localized DC bias was applied on the graphene-BFO hybrid system using scanning probe microscope (AFM) to flip the polarization of BFO from as-grown downward state to upward one. Using spatial resolved Raman spectroscopy and photoelectron spectroscopy (PES), the p-type doping of graphene can be characterized on the downward polarized BFO substrate. A ferroelectric switching to n-type doping of graphene is demonstrated on the upward BFO substrate and with an energy shift of about 0.2 eV higher than Dirac point.

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