Browsing by Author "Huang, P. J."

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Morphology and optical properties of zinc oxide thin films grown on Si (100) by metal-organic chemical vapor deposition
(2009-01-01)
Lan, S. M.
;
Uen, W. Y.
;
Chan, C. E.
;
Chang, K. J.
;
Hung, S. C.
Undoped zinc oxide (ZnO) thin films were deposited on Si (100) substrates by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). After a nucleation layer of ZnO about 500 A... was deposited, top ZnO films with 320-440 nm in thickness were fabricated at temperatures varying from 450 to 600 A degrees C, respectively. X-ray diffraction analyses demonstrate that all the films grown have polycrystalline wurtzite structure. Scanning electron microscopy observations indicate that ZnO films grow with c-axis aligned grains when the deposition temperature is lower than 600 A degrees C. However, 3D microstructures without c-axis alignment were found when the film was deposited at 600 A degrees C. Room temperature photoluminescence (PL) spectra peaking at 3.27-3.29 eV were observed for the ZnO films grown at 450-600 A degrees C. However, only the spectrum from the film grown at 600 A degrees C could present a high intensity ratio of the ultraviolet band to deep-level emissions, which is above 392 and show a minimum full-width at half-maximum of 99 meV for the ultraviolet band. Temperature-dependent PL measurements from 20 to 300 K exhibited the luminescent mechanism of the present ZnO films to be near band excitonic emission.
Optical studies of InN epilayers on Si substrates with different buffer layers
(2007-12-01)
Yang, M. D.
;
Shen, J. L.
;
Chen, M. C.
;
Chiang, C. C.
;
Lan, S. M.
We have investigated the photoluminescence (PL) and time-resolved PL from the InN epilayers grown on Si substrates with different buffer layers. The narrowest value of the full width at half maximum of the PL peak is 52 meV with the AlN/AlGaN/GaN triple buffer layer, which is better than previous reports on similar InN epilayers on Si substrates. Based on the emission-energy dependence of the PL decays, the localization energy of carriers is also the least for the InN with a triple buffer layer. According to the x-ray diffraction measurements, we suggest that the reduced lattice mismatch between the InN epilayer and the top buffer layer is responsible for improvement of sample quality using the buffer-layer technique. (c) 2007 American Institute of Physics.