Water-Gated Charge Doping of Graphene Induced by Mica Substrates

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• 作者：Jihye Shim ; Chun Hung Lui ; Taeg Yeoung Ko ; Young-Jun Yu ; Philip Kim ; Tony F. Heinz ; Sunmin Ryu
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：February 8, 2012
• 年：2012
• 卷：12
• 期：2
• 页码：648-654
• 全文大小：504K
• 年卷期：v.12,no.2(February 8, 2012)
• ISSN：1530-6992

文摘

We report on the existence of water-gated charge doping of graphene deposited on atomically flat mica substrates. Molecular films of water in units of 0.4 nm thick bilayers were found to be present in regions of the interface of graphene/mica heterostacks prepared by micromechanical exfoliation of kish graphite. The spectral variation of the G and 2D bands, as visualized by Raman mapping, shows that mica substrates induce strong p-type doping in graphene with hole densities of (9 卤 2) 脳 10¹² cm^鈥?. The ultrathin water films, however, effectively block interfacial charge transfer, rendering graphene significantly less hole-doped. Scanning Kelvin probe microscopy independently confirmed a water-gated modulation of the Fermi level by 0.35 eV, which is in agreement with the optically determined hole density. The manipulation of the electronic properties of graphene demonstrated in this study should serve as a useful tool in realizing future graphene applications.

Keywords:

Graphene; Raman spectroscopy; mica; charge doping; charge transfer; scanning Kelvin probe microscopy