Symmetrical Dipole Contribution from Planar Defects on m-plane ZnO Epitaxial Films
Chung-Wei Liu, Shoou-Jinn Chang, Yen-Teng Ho, Li Chang, Kuang-Yao Lo and Sanjaya Brahma
Affiliation: Department of Physics, National Cheng Kung University, Tainan 701, Taiwan.
The planar defects such as basal stacking faults (BSFs) are probed on m-plane ZnO grown on LaAlO3(112)
substrate by reflective second harmonic generation (RSHG). The BSFs result in nonvanishing single-direction dipoles that
behave similar to a mirror-like symmetrical dipole. The RSHG pattern from m-plane ZnO comprised of not only the bulk
dipole contribution of ZnO but also an additional mirror-like symmetrical dipole contribution from BSF defects. Transmission
electron microscopy image displays the presence of BSFs that lie in the c-plane of ZnO and agrees well with
RSHG results. Planar BSFs are formed due to the anisotropic stress relaxation between m-plane ZnO film and
LaAlO3(112) substrate, resulting in higher-quality m-plane ZnO films.
Keywords: Basal stacking fault, non-polar plane, second harmonic generation, ZnO.
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