Browsing by Author "Chien, K. F."

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Optical characterization of isoelectronic ZnSe(1-x)O(x) semiconductors
(2011-05-15)
Lin, Y. C.
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Chung, H. L.
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Ku, J. T.
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Chen, C. Y.
;
Chien, K. F.
We have studied the temperature dependence of the band gap and the decay dynamics of isoelectronic ZnSe(1-x)O(x) (x=0-0.053) semiconductors, using photoluminescence (PL) and time-resolved PL spectroscopy. The temperature dependence of the band gap of ZnSe(1-x)O(x) decreases with the increase in 0 concentration. The Kohlrausch law is in good agreement with the O-induced complex decay profiles. As temperature increases, the mechanism of carrier decay undergoes a complicated change from trapped to free excitons. These findings are consistent with the temperature dependence of the stretching exponent beta. (C) 2010 Elsevier B.V. All rights reserved.
Optical characterization of isoelectronic ZnSe1-xOx semiconductors
(2011-05-15)
Lin, Y. C.
;
Chung, H. L.
;
Ku, J. T.
;
Chen, C. Y.
;
Chien, K. F.
We have studied the temperature dependence of the band gap and the decay dynamics of isoelectronic ZnSe1-xOx (x=0-0.053) semiconductors, using photoluminescence (PL) and time-resolved PL spectroscopy. The temperature dependence of the band gap of ZnSe1-xOx decreases with the increase in 0 concentration. The Kohlrausch law is in good agreement with the O-induced complex decay profiles. As temperature increases, the mechanism of carrier decay undergoes a complicated change from trapped to free excitons. These findings are consistent with the temperature dependence of the stretching exponent beta. (C) 2010 Elsevier B.V. All rights reserved.
Optical properties of Zn1-xMnxO thin films grown by molecular beam epitaxy
(2013-09-01)
Chien, K. F.
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Yang, Y. L.
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Tzou, A. J.
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Chou, W. C.
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電子物理學系
Zn(1-x)Mn(x)0 (x=0-0.061) thin films were grown by molecular beam epitaxy (MBE) system. Transmittance shows an increase of the band gap with the increasing Mn concentration. Resonant Raman scattering (RRS) spectra showed 11 longitudinal optical phonon lines for the Zn1-xMnxO samples. For the Zn0.997Mn0.003O sample, circular polarization degree of 9% was observed at magnetic field B=5 T. The dependence of circular polarization rate on the magnetic field intensity exhibits Brillouin type para-magnetism. (c) 2012 Elsevier B.V. All rights reserved.
Quasi-Stranski-Krastanow growth mode of self-assembled CdTe quantum dots grown on ZnSe by molecular beam epitaxy
(2007-04-01)
Yang, C. S.
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Lai, Y. J.
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Chou, W. C.
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Chen, D. S.
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Wang, J. S.
This study investigates the growth mode of highly lattice-mismatch (similar to 14%) CdTe self-assembled quantum dots grown on a ZnSe buffer-layer by molecular beam epitaxy. Two growth processes were used to prepare the samples. For the group-I samples, Te and Cd sources were alternately used to deposit a CdTe coverage layer of 0.6 to 8.0 mono-layers on a Zn-stabilized ZnSe buffer layer. The growth process of group-II samples was reversed; that is, the Cd beam was supplied first on a Se-stabilized ZnSe buffer layer. The optical spectra, including the power-dependent, time-resolved photoluminescence (PL) and PL excitation measurement, demonstrate a ZnTe-like and a CdSe-like two-dimensional precursor layer (wetting layer) in the group-I and group-II samples, respectively. Following the formation of the precursor layer, three-dimensional highly strained CdTe quantum dots were formed. Accordingly, the growth of CdTe self-assembled quantum-dot structures was attributed to the quasi-Stranski-Krastanow mode. (c) 2006 Elsevier B.V. All rights reserved.
The study of self-assembled ZnO nanorods grown on Si(111) by plasma-assisted molecular beam epitaxy
(2013-09-01)
Tzou, A. J.
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Chien, K. F.
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Lai, H. Y.
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Ku, J. T.
;
Lee, L.
The growth and optical properties of self-assembled ZnO nanorods grown on Si(111) substrate by plasma-assisted molecular beam epitaxy (PA-MBE) were studied. By controlling the Zn/O flux ratio, the growth of ZnO nanorods on Si(111) substrate without catalyst has been achieved. Scanning electron microscopy (SEM) shows the ZnO nanorods with various density and diameter could be controlled. Photoluminescence (PL) measurements exhibit nice optical properties. The sharp near band edge PL emission with full width at half maximum (FWHM) of about 17 meV indicates that the ZnO nanorods could be used as the high efficient photonic devices. Crown Copyright (c) 2013 Published by Elsevier B.V. All rights reserved.
Thermal-activated carrier transfer in ZnCdO thin film grown by plasma-assisted molecular beam epitaxy
(2013-09-01)
Chien, K. F.
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Hsu, W. L.
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Tzou, A. J. .
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Lin, Y. C.
;
Chou, W. C.
` The thermal-activated carrier transfer processes in a Zn0.98Cd0.020 thin film grown by plasma-assisted molecular beam epitaxy were investigated using temperature-dependent and time-resolved photoluminescence (PL) spectroscopy. As the temperature increases from 50 to 220 K, the carriers transfer from shallow to deep localized states. Additionally, the carriers escape from the deep localized states above 220 K due to an activation energy of about 19 meV. (c) 2013 Elsevier B.V. All rights reserved.