Jiangtao Wu, Xinghua Shi, Yujie Wei
Lacking a band gap largely limits the application of graphene in electronic devices. Previous study shows that grain boundaries (GBs) in polycrystalline graphene can dramatically alter the electrical properties of graphene. Here, we investigate the band structure of polycrystalline graphene tuned by externally imposed strains and intrinsic mismatch strains at the GB by density functional theory (DFT) calculations. We found that graphene with symmetrical GBs typically has zero band gap even with large uniaxial and biaxial strain. However, some particular asymmetrical GBs can open a band gap in graphene and their band gap can be substantially tuned by external strains. A maximum band gap about 0.28 eV was observed in matched-zigzag GB (13, 0) | (9, 6) with a misorientation of {\theta}=23.4^o when the applied uniaxial strain increases to 9%. The influence of biaxial strains on band gap is always weak. Although mismatch strain is inevitable in asymmetrical GBs, it has a small influence on the band gap of polycrystalline graphene.
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http://arxiv.org/abs/1210.7643
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