Lacking a band gap largely limits the application of graphene in electronic devices. Previous study shows that grain boundaries （GBs） in polycrystalline graphene can dra- matically alter the electrical properties of...Lacking a band gap largely limits the application of graphene in electronic devices. Previous study shows that grain boundaries （GBs） in polycrystalline graphene can dra- matically 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） calcu- lations. We found that graphene with symmetrical GBs typ- ically has zero band gap even with large uniaxial and biax- ial strain. However, some particular asymmetrical GBs can open a band gap in graphene and their band structures can be substantially tuned by external strains. A maximum band gap about 0.19 eV was observed in matched-armchair GB （5, 5） I （3, 7） with a misorientation of θ = 13° when the applied uniaxial strain increases to 9%. Although mismatch strain is inevitable in asymmetrical GBs, it has a small influence on the band gap of polycrystalline graphene.展开更多
基金supported by the National Natural Science Foundation of China(11021262 and 11023001)MOST 973 of China(2012CB937500)
文摘Lacking a band gap largely limits the application of graphene in electronic devices. Previous study shows that grain boundaries （GBs） in polycrystalline graphene can dra- matically 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） calcu- lations. We found that graphene with symmetrical GBs typ- ically has zero band gap even with large uniaxial and biax- ial strain. However, some particular asymmetrical GBs can open a band gap in graphene and their band structures can be substantially tuned by external strains. A maximum band gap about 0.19 eV was observed in matched-armchair GB （5, 5） I （3, 7） with a misorientation of θ = 13° when the applied uniaxial strain increases to 9%. Although mismatch strain is inevitable in asymmetrical GBs, it has a small influence on the band gap of polycrystalline graphene.
