2004年曼徹特大學的Andre Geim與Konstantin Novoselov使用膠帶將石墨烯從高定向熱裂解石墨烯上分離，證明了二維才要可以穩定存在後，眾多科學家爭相投入石墨烯的研究。除了基礎石墨烯物理特性外，石墨烯兼具透明與導電的特性，隨即被應用於光電元件上。光電元件中，入門門檻最低的太陽能電池則為石墨烯應用的首選，而石墨烯/矽蕭特基接面太陽能電池與傳統的ITO蕭特基接面太陽能電池相比，材料與製程上都較為低廉。在2009年IBM團隊首次將石墨烯應用於超高速光感測器，但是石墨烯本身的透光性佳，同時也表示其吸收光能力不足，導致石墨烯的光響應一直無法超越CMOS製程下的光感測器。之後研究石墨烯光感測器也因此多半著重於提升光響應的方向上。除了石墨烯本身材料問題外，在製程方面，欲得到石墨烯薄膜需要經過轉印的步驟，轉印步驟導致了石墨烯無法有效的與CMOS製程結合。本篇論文研究兩種石墨烯薄膜: 經過轉印後的石墨烯與使用ECR-CVD直接成長的石墨烯。兩者分別製作成光感測元件，兩種石墨烯與矽間的蕭特基接面元件特性、兩種光感測元件對光的效能。轉移石墨烯光感測元件在摻雜前的的光響應可達到301 mA/W、摻雜過後可達到302 mA/W。而直接成長石墨烯可以達到90 mA/W。

In 2004,A.K Geim and K.S. Novoselov successfully isolated a single atomic carbon layer from HOPG using mechanical exfoliation methods. Since then, graphene has attracted enormous interest due to its unique properties. Amongst the physical properties of graphene, its high transmittance and conductive properties have shown great potential for photovoltaic applications. Within optoelectronics, the first choice for graphene applications lies within solar cells. Graphene / silicon Schottky junction solar cells, when compared with conventional ITO Schottky junction solar cell reap serious benefits from graphene technology; this in terms not only of device fabrication but also of materials, since graphene can be largely inexpensive to manufacture.
In 2009, an IBM team used graphene for ultrafast optical sensors. Graphene’s high transmittance means light absorption cannot be readily achieved; as such the photo-response of graphene is not good as a CMOS sensor. This work focuses on improving photoresponsivity for graphene photodetectors. In addition to the inherent problem of graphene, obtaining graphene necessarily needs a transfer process, the transfer process lead to graphene being effectively combined with the CMOS process. This thesis uses two methods of obtaining graphene: Graphene from transfer process and graphene directly grown on silicon substrate by ECR-CVD. We fabricate two kinds of graphene-Schoktty junction photodetector. We analyze their junction characteristic and their photoelectric effect. The responsivity of pristine transfer graphene device is 301mA/W, doped transfer graphene device is 302 mA/W and ECR graphene device is 90mA/W.

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