Self-Encapsulated Doping of n-Type Graphene Transistors with Extended Air Stability

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• 作者：Po-Hsun Ho ; Yun-Chieh Yeh ; Di-Yan Wang ; Shao-Sian Li ; Hsin-An Chen ; Yi-Hsuan Chung ; Chih-Cheng Lin ; Wei-Hua Wang ; Chun-Wei Chen
• 刊名：ACS Nano
• 出版年：2012
• 出版时间：July 24, 2012
• 年：2012
• 卷：6
• 期：7
• 页码：6215-6221
• 全文大小：415K
• 年卷期：v.6,no.7(July 24, 2012)
• ISSN：1936-086X

文摘

This paper presents an innovative approach to fabricating controllable n-type doping graphene transistors with extended air stability by using self-encapsulated doping layers of titanium suboxide (TiOx) thin films, which are an amorphous phase of crystalline TiO₂ and can be solution processed. The nonstoichiometry TiOx thin films consisting of a large number of oxygen vacancies exhibit several unique functions simultaneously in the n-type doping of graphene as an efficient electron-donating agent, an effective dielectric screening medium, and also an encapsulated layer. A novel device structure consisting of both top and bottom coverage of TiOx thin layers on a graphene transistor exhibited strong n-type transport characteristics with its Dirac point shifted up to 鈭?0 V and an enhanced electron mobility with doping. Most interestingly, an extended stability of the device without rapid degradation after doping was observed when it was exposed to ambient air for several days, which is not usually observed in other n-type doping methods in graphene. Density functional theory calculations were also employed to explain the observed unique n-type doping characteristics of graphene using TiOx thin films. The technique of using an 鈥渁ctive鈥?encapsulated layer with controllable and substantial electron doping on graphene provides a new route to modulate electronic transport behavior of graphene and has considerable potential for the future development of air-stable and large-area graphene-based nanoelectronics.

Keywords:

graphene; TiOx; n-type doping of graphene and transistor; air stability