Browsing by Author "Lo, Kuang-Yao"

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Optical second harmonic generation from the twin boundary of ZnO thin films grown on silicon
(2008-03-03)
Lo, Kuang-Yao
;
Lo, Shih-Chieh
;
Yu, Chang-Feng
;
Tite, Teddy
;
Huang, Jung-Y.
The symmetry of the twin boundaries of ZnO epitaxial film was detected with reflective second harmonic generation (RSHG). The twin boundaries exhibit mirror symmetry with a polar configuration across the boundary plane and yield a nonvanishing polar contribution to RSHG. The nonvanishing second-order susceptibility supports the notion that the measured RSHG originates from the planar defect, which depends on the residual stress in the thin film. We analyzed our RSHG result by correlating the macroscopic data from optic probe with the microscopic data from tunneling electron microscope.
Symmetrical Dipole Contribution from Planar Defects on m-plane ZnO Epitaxial Films
(2014-01-01)
Liu, Chung-Wei
;
Chang, Shoou-Jinn
;
Ho, Yen-Teng
;
Chang, Li
;
Lo, Kuang-Yao
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.