標題: Opening an Electrical Band Gap of Bilayer Graphene with Molecular Doping
作者: Zhang, Wenjing
Lin, Cheng-Te
Liu, Keng-Ku
Tite, Teddy
Su, Ching-Yuan
Chang, Chung-Huai
Lee, Yi-Hsien
Chu, Chih-Wei
Wei, Kung-Hwa
Kuo, Jer-Lai
Li, Lain-Jong
材料科學與工程學系
光電工程學系
Department of Materials Science and Engineering
Department of Photonics
關鍵字: bilayer graphene;band gap opening;transistor;Raman spectroscopy;doping;on/off current ratio;triazine
公開日期: 1-九月-2011
摘要: The opening of an electrical band l gap in graphene Is crucial for its application for logic circuits. Recent studies have shown that an energy gap in Bernal-stacked bilayer graphene can be generated by applying an electric displacement field. Molecular doping has also been proposed to open the electrical gap of bilayer graphene by breaking either in-plane symmetry or inversion symmetry; however, no direct observation of an electrical gap has been reported. Here we discover that the organic molecule triazine is able to form a uniform thin coating on the top surface of a bilayer graphene, which efficiently blocks the accessible doping sites and prevents ambient p-doping on the top layer. The charge distribution asymmetry between the top and bottom layers can then be enhanced simply by increasing the p-doping from oxygen/moisture to the bottom layer. The on/off current ratio for a bottom-gated bilayer transistor operated in ambient condition Is improved by at least 1 order of magnitude. The estimated electrical band gap is up to similar to 111 meV at room temperature. The observed electrical band gap dependence on the hole-carrier density increase agrees well with the recent density-functional theory calculations. This research provides a simple method to obtain a graphene bilayer transistor with a moderate on/off current ratio, which can be stably operated in air without the need to use an additional top gate.
URI: http://dx.doi.org/10.1021/nn202463g
http://hdl.handle.net/11536/19437
ISSN: 1936-0851
DOI: 10.1021/nn202463g
期刊: ACS NANO
Volume: 5
Issue: 9
起始頁: 7517
結束頁: 7524
顯示於類別:期刊論文


文件中的檔案:

  1. 000295187400086.pdf