论文部分内容阅读
Controlling the atomic configurations of structural defects in graphene nanostructures is crucial for achieving desired functionalities.Here,we report the controlled fabrication of high-quality single-crystal and bicrystal graphene nanoislands(GNI)through a unique top-down etching and post-annealing procedure on a graphite surface.Low-temperature scanning tunneling microscopy(STM)combined with density functional theory calculations reveal that most of grain boundaries(GBs)formed on the bicrystal GNIs are 5-7-5-7 GBs.Two nanodomains separated by a 5-7-5-7 GB are AB stacking and twisted stacking with respect to the underlying graphite substrate and exhibit distinct electronic properties,forming a graphene homojunction.In addition,we construct homojunctions with alternative AB/twisted stacking nanodomains separated by parallel 5-7-5-7 GBs.Remarkably,the stacking orders of homojunctions are manipulated from AB/twist into twist/twist type through a STM tip.The controllable fabrication and manipulation of graphene homojunctions with 5-7-5-7 GBs and distinct stacking orders open an avenue for the construction of GBs-based devices in valleytronics and twistronics.