Fig. 4
From: Interfaces between hexagonal and cubic oxides and their structure alternatives
Orientation relationship for m-ZnO. Scanning transmission electron microscopy (STEM)- high-angle annual dark-field (HAADF) images of (a) m-ZnO-I and (b) m-ZnO-II domains of the m-plane film. Scale bar, 2 nm. The insets show the magnified images from the area outlined by the yellow rectangles with the atomic projection of [011]mZnO-I in a and [0–83]mZnO-II in b embedded. The inset outlined by white line squares in a, b are calculated STEM-HAADF images along [011]ZnO and [08–3]ZnO, respectively. They agree with the experimental images very well. Note, there are 5 ~ 6 atomic layers in the interface that have an atomic arrangement similar to MgO, as marked by a pair of orange vertical dashed lines. The image intensity decreases from the ZnO film to the MgO substrate over these layers, as indicated by the embedded image intensity line scans (red) from the red dashed rectangles (integrated vertically). This indicates that there exists an interface phase Zn x Mg1−x O (x decreases from the ZnO film side to the MgO substrate side, see Supplementary Note 9 for electron energy loss spectroscopy (EELS) analysis). The two green dashed arrows in a indicate the alignment of a ZnO row with an MgO row. c Projection of the interface for m-ZnO-I along [011] direction (upper panel) and m-ZnO-II along [08–3] direction (lower panel) derived from STEM images. d Top view (one layer of a (100)ZnO plane on top of one layer of a (001)MgO plane) of the interface area outlined by the brown rectangle in c (rotated 90° clockwise). The m-ZnO-II domain (lower panel) can be obtained by rotating 90° from m-ZnO-I (upper panel)
