本論文研究成長在碳化矽(SiC)基板上的石墨烯，包含存在緩衝層(Buffer layer)的MLG(Monolayer Graphene)與無緩衝層的QFMLG(Quasi-Free-Standing Monolayer Graphene)，以原子力顯微鏡(AFM)對石墨烯表面進行侷域陽極氧化(LAO)。經LAO後之區域以拉曼光譜和光電子能譜測量，發現不同的基板-石墨烯介面對結果有極大的影響：QFMLG樣品中碳化矽基板被氧化成二氧化矽(SiO2)，石墨烯並未被氧化而是變成與基板有較強鍵結的緩衝層；MLG樣品中基板氧化成二氧化矽，石墨烯氧化成石墨烯氧化物(Graphene Oxide)。利用LAO劃出氧化方框後，以鎢針對框內-框外進行電流-電壓量測，發現QFMLG樣品上的系統具有整流特性，此一結果可用兩個背靠背(back-to-back)串聯的蕭特基位障(Schottky barrier)形成金屬─半導體─金屬結構來解釋，由LAO劃線形成封閉區域使得框內外的石墨烯功函數不同，產生內外側不同的蕭特基位障。LAO參數可改變蕭特基位障的差異，氧化的程度越高，系統整流的效果越好，實驗中電流的開關比(On-Off ratio)最高達到441.5。

In this study, local anodic oxidation (LAO) of graphene on SiC substrates is carried out using atomic force microscope (AFM). From Raman spectroscopy and photoelectron spectroscopy (PES), LAO regions of graphene on SiC substrates with and without buffer layer (i.e., Monolayer Graphene, MLG and Quasi-Free-Standing Monolayer Graphene, QFMLG, respectively) have great differences: For QFMLG sample, only SiC substrate is oxidized into SiO2, while graphene exhibit strong interaction with the substrate and become buffer layer. On the other hand, the oxidation of both graphene and SiC substrate were observed in MLG sample. After LAO nano-patterning, open square patterns were made and current-voltage measurements are conducted using W-tips which placed inside and outside of the square patterns. Systems on the QFMLG sample reveal rectifying characteristic, which can be modeled by a metal-semiconductor-metal structure involving two back-to-back Schottky barriers. LAO patterning results in work function differences between inner and outer graphene, which lead to different Schottky barriers. These differences can be tuned by changing the LAO parameters, showing that the rectifying ability increased with the degree of oxidation. The current on-off ratio achieved 441.5 in this study.

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