Molecular Doping and Band-Gap Opening of Bilayer Graphene
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- 作者：Alexander J. Samuels ; J. David Carey
- 刊名：ACS Nano
- 出版年：2013
- 出版时间：March 26, 2013
- 年：2013
- 卷：7
- 期：3
- 页码：2790-2799
- 全文大小：503K
- 年卷期：v.7,no.3(March 26, 2013)
- ISSN：1936-086X
文摘
The ability to induce an energy band gap in bilayer graphene is an important development in graphene science and opens up potential applications in electronics and photonics. Here we report the emergence of permanent electronic and optical band gaps in bilayer graphene upon adsorption of 蟺 electron containing molecules. Adsorption of n- or p-type dopant molecules on one layer results in an asymmetric charge distribution between the top and bottom layers and in the formation of an energy gap. The resultant band gap scales linearly with induced carrier density though a slight asymmetry is found between n-type dopants, where the band gap varies as 47 meV/1013 cm鈥?, and p-type dopants where it varies as 40 meV/1013 cm鈥?. Decamethylcobaltocene (DMC, n-type) and 3,6-difluoro-2,5,7,7,8,8-hexacyano-quinodimethane (F2-HCNQ, p-type) are found to be the best molecules at inducing the largest electronic band gaps up to 0.15 eV. Optical adsorption transitions in the 2.8鈥? 渭m region of the spectrum can result between states that are not Pauli blocked. Comparison is made between the band gaps calculated from adsorbate-induced electric fields and from average displacement fields found in dual gate bilayer graphene devices. A key advantage of using molecular adsorption with 蟺 electron containing molecules is that the high binding energy can induce a permanent band gap and open up possible uses of bilayer graphene in mid-infrared photonic or electronic device applications.