title: Migration mechanism of a GaN bicrystalline grain boundary as a model system.
abstract: Using in situ high-resolution transmission electron microscopy, we have explored migration mechanism of a grain boundary in a GaN bicrystal as a model system. During annealing at 500 °C, the grain-boundary region underwent a decrease in thickness, which occurred by decomposition or sublimation of GaN during annealing at 500 °C coupled with electron-beam sputtering. The decrease in thickness corresponds to an increase in the driving force for migration, because the migration of the grain boundary was driven by the surface energy difference. As the driving force increased with annealing time, the grain-boundary morphology turned from atomically smooth to rough, which is characterized by kinetic roughening. The observations indicate that a grain boundary exhibits a nonlinear relationship between driving force for migration and migration velocity, in discord with the general presumption that a grain boundary follows a linear relationship.
authors.affiliation: Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, South Korea.
authors.forename: Sung Bo
authors.initials: SB
authors.lastname: Lee
authors.affiliation: Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute, Daejeon 34133, South Korea.
authors.forename: Seung Jo
authors.initials: SJ
authors.lastname: Yoo
authors.affiliation: IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science, Sungkyunkwan University, Suwon 16419, South Korea.|Department of Energy Science, Sungkyunkwan University, Suwon 16419, South Korea.
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Kim
authors.affiliation: Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute, Daejeon 34133, South Korea.
authors.forename: Jin-Gyu
authors.initials: JG
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, South Korea.
authors.forename: Heung Nam
authors.initials: HN
authors.lastname: Han