Browsing by Author "Liu, Shiu-Jen"

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Effects of Cr doping on physical properties of amorphous In-Ga-Zn-O films
(2011-09-15)
Liu, Shiu-Jen
;
Su, Shih-Hao
;
Fang, Hau-Wei
;
Hsieh, Jang-Hsing
;
Juang, Jenh-Yih
Amorphous thin films of InGaZnO(4) (a-IGZO) doped with Cr have been fabricated by using pulsed-laser deposition (PLD). The electrical, optical and magnetic properties of Cr-doped a-IGZO films grown at 25 degrees C and 150 degrees C were investigated. The conductivity, optical transmission and band gap of films are remarkably enhanced by increasing the growth temperature. Conductivity, carrier concentration and mobility decrease with increasing the Cr content. However, the optical transmission and band gap are not significantly affected by Cr doping. Moreover, all Cr-doped films exhibit room-temperature ferromagnetism. (C) 2011 Elsevier B.V. All rights reserved.
Effects of growth temperature on Mg-doped ZnO films fabricated by pulsed-laser deposition
(2017-01-01)
Fang, Hau-Wei
;
Juang, Jenh-Yih
;
Liu, Shiu-Jen
;
材料科學與工程學系
;
電子物理學系
Magnesium-doped zinc oxide (MZO) films were fabricated by pulsed-laser deposition (PLD) at various substrate temperatures (T-s). The substitution of Mg for Zn sites (Mg-Zn) in the films was confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and room-temperature photoluminescence (RTPL) measurements. Characteristic deep-level emissions (DLE) observed in the RTPL spectra further indicate the presence of Zn vacancies (V-Zn) in the MZO films. Moreover, it was found that the intensity of the blue emission corresponding to V-Zn increases with increasing T-s, indicating the important role played by T-s on the incorporation of Mg into ZnO matrix. Hall effect measurements reveal the p-type conduction of the MZO films grown at 400 degrees C. The p-type characteristic is attributed to the formation of nMg(Zn) - V-Zn complex which could act as acceptor for MZO films.
Fabrication and characterization of amorphous In Zn-O/SiO(x)/n-Si heterojunction solar cells
(2011-11-01)
Fang, Hau-Wei
;
Liu, Shiu-Jen
;
Hsieh, Tsung-Eong
;
Juang, Jenh-Yih
;
Hsieh, Jang-Hsing
Amorphous In-Zn-O (a-IZO) films were deposited on SiO(x) covered n-type Si substrates by using pulsed laser deposition (PLD) technique to form a-IZO/SiO(x)/n-Si heterojunction solar cells. The a-IZO films grown at 150 degrees C with various laser power (250-500 mJ/pulse) exhibit low resistivity (2-3 x 10(-3) Omega cm) and high transparency (similar to 80%) in the visible wavelength range. The highest conversion efficiency of the fabricated a-IZO/SiO(x)/n-Si solar cells is 2.2% under 100 mW/cm(2) illumination (AM 1.5 condition). The open-circuit voltage, short-circuit current density and fill factor of the best device are 0.24 V, 28.4 mA/cm(2) and 33.6%, respectively. (C) 2011 Elsevier Ltd. All rights reserved.
Fabrication and characterization of amorphous In Zn-O/SiOx/n-Si heterojunction solar cells
(2011-11-01)
Fang, Hau-Wei
;
Liu, Shiu-Jen
;
Hsieh, Tsung-Eong
;
Juang, Jenh-Yih
;
Hsieh, Jang-Hsing
Amorphous In-Zn-O (a-IZO) films were deposited on SiOx covered n-type Si substrates by using pulsed laser deposition (PLD) technique to form a-IZO/SiOx/n-Si heterojunction solar cells. The a-IZO films grown at 150 degrees C with various laser power (250-500 mJ/pulse) exhibit low resistivity (2-3 x 10(-3) Omega cm) and high transparency (similar to 80%) in the visible wavelength range. The highest conversion efficiency of the fabricated a-IZO/SiOx/n-Si solar cells is 2.2% under 100 mW/cm(2) illumination (AM 1.5 condition). The open-circuit voltage, short-circuit current density and fill factor of the best device are 0.24 V, 28.4 mA/cm(2) and 33.6%, respectively. (C) 2011 Elsevier Ltd. All rights reserved.
Influence of oxygen vacancies on transport properties of La2/3Ca1/3MnO3-y films grown on SrTiO3 substrates
(2007-10-01)
Liu, Shiu-Jen
;
Chen, Shyh-Fen
;
Juang, Jenh-Yih
;
Lin, Jiunn-Yun
;
Wu, Kaung-Hsiung
We prepared La2/3Ca1/3MnO3-y films with various oxygen contents on SrTiO3 substrates and measured the temperature-dependent resistivity of the manganite films under tensile stress due to the lattice mismatch between manganites and single-crystal substrates. The effect of oxygen vacancies on the transport properties of the films was investigated. The experimental results reveal that the dependence of temperature on the resistivity of fully oxygenated films can be attributed to the adiabatic small-polaron conduction and unconventional one-magnon scattering at temperatures above and far below the insulator-metal (I-M) transition temperature, respectively. However, for highly oxygen -deficient films, the temperature-dependent resistivity can be ascribed to Mott's variable-range-hopping and small polaron metallic conduction at temperatures above and far below the I-M transition temperature, respectively.
Metal-insulator transition characteristics of Mo- and Mn-doped VO2 films fabricated by magnetron cosputtering technique
(2014-06-01)
Liu, Shiu-Jen
;
Fang, Hau-Wei
;
Su, Yu-Tai
;
Hsieh, Jang-Hsing
;
材料科學與工程學系
Mo- and Mn-doped VO2 thin films have been grown on c-cut sapphire substrates by the magnetron co-sputtering technique. The effects of Mo and Mn doping on the structure and metal-insulator transition of the doped VO2 thin films were studied. An enlargement of the out-of-plane lattice constant of the film caused by Mo doping was observed. As expected, the transition temperature (T-MI) is reduced by Mo doping. However, the valence of the Mo ions doped in the VO2 films is determined by X-ray photoelectron spectroscopy to be 6+ on the surface, but 4+ and 3+ in the bulk part of the films. The reduction in T-MI observed in this study is attributed to the variation in the band structure resulting from the incorporation of Mo4+ into the VO2 lattice. The optical transmission is remarkably enhanced by low-concentration Mo doping and then monotonically decreases with increasing Mo content. On the other hand, the out-of-plane lattice constant and T-MI are not affected by Mn doping. The transmission is enhanced and then monotonically increases with increasing Mn concentration. The thermochromism of doped films is suppressed by Mo and Mn doping. (C) 2014 The Japan Society of Applied Physics
Physical properties of amorphous InGaZnO(4) films doped with Mn
(2009-03-02)
Liu, Shiu-Jen
;
Fang, Hau-Wei
;
Su, Shih-Hao
;
Li, Chia-Hung
;
Cherng, Jyh-Shiarn
Amorphous InGaZnO(4) (a-IGZO) films doped with various concentrations of Mn have been fabricated by using pulsed-laser deposition technique. Optical, electrical, and magnetic properties of the prepared Mn-doped a-IGZO films were investigated. The resistivity, carrier concentration, and carrier mobility of the a-IGZO films were found to be, respectively, increased, decreased, and enhanced by Mn doping. Moreover, the optical transmission is slightly increased in the visible range and the optical band gaps are not affected in the Mn-doped films. Room-temperature ferromagnetism has been observed in the field-dependent magnetization measurements.
Physical properties of amorphous InGaZnO4 films doped with Mn
(2009-03-02)
Liu, Shiu-Jen
;
Fang, Hau-Wei
;
Su, Shih-Hao
;
Li, Chia-Hung
;
Cherng, Jyh-Shiarn
Amorphous InGaZnO4 (a-IGZO) films doped with various concentrations of Mn have been fabricated by using pulsed-laser deposition technique. Optical, electrical, and magnetic properties of the prepared Mn-doped a-IGZO films were investigated. The resistivity, carrier concentration, and carrier mobility of the a-IGZO films were found to be, respectively, increased, decreased, and enhanced by Mn doping. Moreover, the optical transmission is slightly increased in the visible range and the optical band gaps are not affected in the Mn-doped films. Room-temperature ferromagnetism has been observed in the field-dependent magnetization measurements.
Physical properties of amorphous Mo-doped In-Ga-Zn-O films grown by magnetron co-sputtering technique
(2012-06-01)
Liu, Shiu-Jen
;
Fang, Hau-Wei
;
Hsieh, Jang-Hsing
;
Juang, Jenh-Yih
;
材料科學與工程學系
Amorphous thin films of In-Ga-Zn-O (a-IGZO) doped with Mo have been fabricated by using magnetron co-sputtering technique. The Mo concentration in a-IGZO films was modulated by varying the sputtering power applied on the Mo target. The electrical, optical and magnetic properties of Mo-doped a-IGZO films grown on glasses were investigated. The carrier density and mobility of a-IGZO films can be remarkably enhanced by low concentration Mo doping. On the other hand, the optical bandgap of a-IGZO films is not significantly affected by Mo doping. However, the transmission is decreased with increasing the Mo doping. Moreover, all Mo-doped films exhibit room-temperature ferromagnetism. (C) 2012 Elsevier Ltd. All rights reserved.
Physical properties of polycrystalline Cr-doped SnO(2) films grown on glasses using reactive dc magnetron co-sputtering technique
(2011-01-01)
Liu, Shiu-Jen
;
Chen, Liang-Yu
;
Liu, Chai-Yun
;
Fang, Hau-Wei
;
Hsieh, Jang-Hsing
Electrical, optical and magnetic properties of polycrystalline Cr-doped SnO(2) films grown on glasses using reactive dc magnetron co-sputtering technique were investigated. The Cr content was modulated by varying the sputtering power applied on the Cr target. The carrier concentration and conductivity of doped films are reduced with increasing the Cr doping. Moreover, while the Cr content ratio Cr/( Sn + Cr) exceeds 0.9 at.%, the doped SnO(2) films become insulators and the optical transmission is strongly affected. The surface roughness of sputtered films is also increased by Cr doping. The co-sputtered Cr-doped SnO(2) films exhibit paramagnetic characteristics from room temperature down to 25 K. (C) 2010 Elsevier B.V. All rights reserved.
Physical properties of polycrystalline Cr-doped SnO2 films grown on glasses using reactive dc magnetron co-sputtering technique
(2011-01-01)
Liu, Shiu-Jen
;
Chen, Liang-Yu
;
Liu, Chai-Yun
;
Fang, Hau-Wei
;
Hsieh, Jang-Hsing
Electrical, optical and magnetic properties of polycrystalline Cr-doped SnO2 films grown on glasses using reactive dc magnetron co-sputtering technique were investigated. The Cr content was modulated by varying the sputtering power applied on the Cr target. The carrier concentration and conductivity of doped films are reduced with increasing the Cr doping. Moreover, while the Cr content ratio Cr/( Sn + Cr) exceeds 0.9 at.%, the doped SnO2 films become insulators and the optical transmission is strongly affected. The surface roughness of sputtered films is also increased by Cr doping. The co-sputtered Cr-doped SnO2 films exhibit paramagnetic characteristics from room temperature down to 25 K. (C) 2010 Elsevier B.V. All rights reserved.
Room-temperature ferromagnetism in amorphous In-Ga-Zn-O films fabricated by using pulsed-laser deposition
(2014-09-01)
Liu, Shiu-Jen
;
Su, Shih-Hao
;
Juang, Jenh-Yih
;
電子物理學系
;
Department of Electrophysics
Room-temperature ferromagnetism (RTFM) was observed in pulsed-laser deposited amorphous In-Ga-Zn-O (a-IGZO) films undoped with impurities containing unpaired d or f electrons. The presence of oxygen vacancies in the prepared a-IGZO films was verified by X-ray photoelectron spectroscopy and suggested to be responsible for the observed RTFM. The electrical and optical properties of the a-IGZO films were also investigated.
Room-temperature ferromagnetism in carbon- and nitrogen-doped rutile TiO2
(2015-02-01)
Wang, Jia-Bin
;
Wu, Kuei-Ching
;
Mi, Jyun-Wei
;
Luo, Chih-Wei
;
Wu, Kaung-Hsiung
Marked room-temperature ferromagnetism (RTFM) was obtained in carbon- and nitrogen-doped rutile powders. X-ray photoelectron spectroscopy measurements revealed the co-existence of considerable densities of states near the Fermi level () and oxygen vacancies primarily induced by C- and N-doping. Density functional theory calculations showed that the local moments responsible for the observed RTFM in N-doped were primarily attributed to the partially populated, spin-polarized Ti band. In addition to the unfilled Ti band, the spin splitting in C states near in C-doped , which may be induced by the interaction between the C impurities and neighboring oxygen ions, results in Stoner band-splitting-type ferromagnetism.