Band Gap Opening of Graphene by Forming Heterojunctions with the 2D Carbonitrides Nitrogenated Holey Graphene, g-C3N4, and g-CN: Electric Field Effect

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• 作者：Xiong Cao ; Jun-jie Shi ; Min Zhang ; Xin-he Jiang ; Hong-xia Zhong ; Pu Huang ; Yi-min Ding ; Meng Wu
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 26, 2016
• 年：2016
• 卷：120
• 期：20
• 页码：11299-11305
• 全文大小：597K
• 年卷期：0
• ISSN：1932-7455

文摘

To solve a challenging issue, i.e., the gap opening of graphene, we designed several heterojunctions of graphene and other two-dimensional carbonitride materials with natural holes in their monolayers, namely, nitrogenated holey graphene (NHG), g-C₃N₄, and g-CN, to destroy graphene’s sublattice symmetry and we investigated their electronic structures by first-principles calculations, in which the external electric field effect was also considered. We found that the heterojunctions, except for that with g-CN, have a direct band gap and that their important band edge states are dominated mainly by their graphene layer. The electric field can open band gaps and reduce the effective mass of electron and hole. The graphene/NHG has a large band gap (186.6 meV) and electron effective mass, which can be reduced from 1.31 to 0.014 m₀ by applying an electric field of 0.4 V/Å. The NHG/graphene/NHG has the largest band gap of 250.7 meV among all of the graphene-based heterojunctions. The band gap of g-C₃N₄/graphene/g-C₃N₄ can be enlarged from 76.8 to 85.5 meV by applying a perpendicular electric field (0.6 V/Å). Interestingly, the external electric field can also convert the indirect band gap of graphene/g-CN into a direct one of 83.3 meV. Our results are useful for fast graphene-based nano-optoelectronic devices.