Atomic structural variations of [0Â 0Â 0Â 1]-tilt grain boundaries during ZnO grain growth occurred by thermal treatments

▶ Plane-view zero-loss energy filtered transmission electron microscopy images showed that the [0 0 0 1]-tilt grain boundary of as-grown ZnO thin films changed from the zigzag facet planes into the symmetric tilt grain boundary through the asymmetric tilt grain boundary with periodic {011¯0}/{358¯0} flat planes. Such an atomic structural variations of grain boundary changes from curved grain boundaries to flat shape was due to decrease of total boundary energy during grain growth.