Figure 2.

RHEED results. (a) RHEED pattern of the MgO (001) substrate prior to the ZnO film growth along the [001] azimuth. (b) RHEED pattern of the ZnO film surface grown at 420°C along the [1-210] azimuth. (c) RHEED pattern of the nonpolar single crystal ZnO surface along the [1-210] azimuth. (d) RHEED pattern of the polar homoepitaxial ZnO film surface along the [1-10] azimuth. (e) RHEED pattern of the ZnO film surface grown at 100°C, which shows the combination of the [1-10] and [1-210] azimuths. This indicates of the coexistence of two domains. (f) RHEED pattern of the polar homoepitaxial ZnO film polar surface along the [1-210] azimuth.