Defects in m-plane ZnO epitaxial films grown on (112) LaAlO₃ substrate

The crystallographic orientations of m-plane ZnO on (112) LaAlO₃ (LAO) substrate are [1210]_ZnO||[111]_LAO and [0001]_ZnO||[110]_LAO. The defects in m-plane ZnO have been systematically investigated using cross section and plan-view transmission electron microscopy (TEM). High-resolution TEM observations in cross section show misfit dislocations and basal stacking faults (BSFs) at the ZnO/LAO interface. In the films, threading dislocations (TDs) with 1/3<1120> Burgers vectors are distributed on the basal plane, and BSFs have 1/6<2023> displacement vector. The densities of dislocations and BSFs are estimated to be 5.1×10¹⁰ cm^-2 and 4.3×10⁵ cm^-1, respectively. In addition to TDs and BSFs, plan-view TEM examination also reveals that stacking mismatch boundaries mainly lie along the m-planes and they connect with planar defect segments along the r-planes.