石墨烯為原子級二維薄膜，擁有高比表面積及高載子遷移率等特性，可望超越現今的矽等半導體材料。然而由於吸附空氣中的氧原子及水氣造成原生的p型摻雜，因此改變石墨烯的電子結構一直是重要課題。其中氮摻雜可使石墨烯從p型轉變成n型。本研究以化學氣相沉積合成多層石墨烯，將其暴露於氮氣電漿中，利用遮罩定義摻雜區域後製作pn二極體，並做其電性分析及應用於半波整流電路中。透過調變氮氣電漿功率使石墨烯電晶體在電流-電壓特性曲線中的狄拉克點(導電率最低點)從正區(+75 V)逐漸偏移至負區(-55 V)，成功使石墨烯轉成n型半導體。隨著電漿功率的提高氮含量從1.4%增加至2.8%，其中C-N鍵結方式中的Pyrrolic-N明顯隨功率增加而增加，是石墨烯轉變成n型半導體的關鍵。此外由拉曼光譜可知，摻雜後的石墨烯缺陷峰變大。石墨烯同質接面二極體具有整流特性，且於示波器中顯示半波整流的波形，表示有良好的截波的作用，未來將可進一步應用於金氧半電晶體及雙極性電晶體等元件。

Graphene is a two dimensional material with high surface area and high carrier mobility. Graphene is an attractive candidate for potential applications in optical and electrical devices due to these outstanding properties. Pristine graphene usually exhibits p-type behavior owing to the adsorption of oxygen and water vapor from the air. Therefore, modulating the grapheme electronic structure is an essential issue. Nitrogen doping is a facile approach used to tune the Fermi level above the Dirac point. Multi-layer graphene was synthesized in this study using chemical vapor deposition and then treated using nitrogen plasma. Under nitrogen plasma exposure the lateral graphene p-n junction was formed with the mask defining the doping regime. We investigated the device electrical characteristics using the half-wave rectifier. By modulating the nitrogen plasma power the current-voltage curve shows the Dirac point shifted from a positive value (+75 V) to a negative value (-55 V), indicating successful grapheme transformation into an n-type semiconductor. The nitrogen content increased from 1.4% to 2.8% with increased power. Pyrrolic-N content increased leading graphene FET to act as an n-type semiconductor. As shown from the Raman spectrum, the doping process induced defects. The graphene lateral homojunction exhibited diode properties. Good rectifier performance with very low distortion was identified by the oscilloscope. This device could be further applied in metal-oxide-semiconductor field-effect transistors and bipolar junction transistors.

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