Browsing by Author "Fang, Hau-Wei"

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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.
Effects of indium concentration on the efficiency of amorphous In-Zn-O/SiOx/n-Si hetero-junction solar cells
(2014-02-01)
Fang, Hau-Wei
;
Hsieh, Tsung-Eong
;
Juang, Jenh-Yih
;
材料科學與工程學系
;
電子物理學系
Semiconductor-insulator-semiconductor (SIS) hetero-junction solar cells comprising of the amorphous indium zinc oxide (a-IZO) layer directly deposited onto the n-type Si substrates by pulsed laser deposition were fabricated. Characterizations on the physical properties of the a-IZO layer and the a-IZO/SiOx interface as a function of In/(Zn + In) ratio were carried out to delineate their influences on the photovoltaic performance of SIS solar cells. The optical and electrical analyses indicated that the resistivity of a-IZO films decreased with increasing In concentration, reaching 4.5 x 10(-4) Omega-cm for In/ (Zn+In)=0.5, which also exhibited a transmittance higher than 80% in the visible-light wavelength range. Moreover, combining with an optimally controlled insulating SiOx layer (about 2.0 nm), the device exhibited excellent SIS solar cell performance with open-circuit voltage of 0.38 V, short-circuit current density of 45.1 mA cm(-2), fill factor of 49.7% and a conversion efficiency of 8.4% under the AM1.5 illumination condition. The dramatic performance enhancement was attributed to the reduction of effective interface trap densities at the a-IZO/SiOx interface and the increase of carrier mobility in the a-IZO layer resulted from the increase of In/(In+Zn) ratio. (C) 2013 Elsevier B.V. All rights reserved.
Effects of Strain and Ordering of Rare-Earth Element Moments on Magnetic-Reordering in Orthorhombic Multiferroic Manganites
(2013-10-01)
Hsiao, Yen-Fu
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Lai, Jun-Yo
;
Lin, Jun-Yu
;
Fang, Hau-Wei
;
Hung, Yi-Tse
Orthorhombic multiferroic manganite thin films with various orientations and strain states were prepared to show the effects of anisotropic strain and antiferromagnetic (AFM) ordering of rare-earth f-electrons on the orientation of the incommensurate-to-commensurate AFM reordering. Systematic analyses suggest that the low-temperature AFM ordering of the rare-earth f-electrons may have played a decisive role in causing the orientation changes in AFM reordering, although the b-axis strain does have a significant influence on the zero-field magnetization behaviors. (C) 2013 The Japan Society of Applied Physics
Effects of strain on the electronic structure and magnetic properties in SrMn0.5Fe0.5O3
(2016-09-01)
Mi, Chun-Wei
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Chin, Yi-Ying
;
Hsiao, Yen-Fu
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Fang, Hau-Wei
;
Luo, Chih-Wei
The electronic structure and magnetic properties of SrMn0.5Fe0.5O3 powder and films grown on (100)-SrTiO3 (STO) and (100)-LaAlO3 (LAO) substrates by pulsed laser deposition (PLD) were investigated by temperature dependent magnetization and soft x-ray absorption. The results exhibit characteristics of 3d(5) Fe3+, 3d(5) (L) under bar Fe4+, and 3d(3) + 3d(4) (L) under bar Mn4+ at room temperature in all samples. However, the features of 3d(5) Fe3+ and 3d(3) Mn4+ increased significantly for SMFO/LAO at 35 K, which also displayed substantial competition between antiferromagnetic and ferromagnetic order well-above the Neel temperature of SrFeO3 (T-N similar to 134 K). We attributed this to being caused by charge disproportionation resulting from ligand-hole localization, which is more favorable to take place when the sample is under compressive strain.
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.
Influences of SiOx layer thickness on the characteristics of In-Zn-O/SiOx/n-Si hetero-junction structure solar cells
(2013-09-01)
Fang, Hau-Wei
;
Hsieh, Tsung-Eong
;
Juang, Jenh-Yih
;
材料科學與工程學系
;
電子物理學系
Indium zinc oxide (IZO) film was directly deposited on an n-type Si substrate by pulsed laser deposition (PLD) to form the IZO/SiOx/n-Si hetero-junction solar cell. Analytical results indicated that the thickness and quality of the thermal SiOx layer plays a prominent role in determining the conversion efficiency of the solar cell. The sample containing an about 1.78-nm-thick SiOx layer exhibits an open-circuit voltage of 035 V, a short-circuit current density of 28.6 mA/cm(2), a fill factor of 34.3%, and an overall conversion efficiency of 3.4% under AM1.5 condition. The effects of the SiOx layer thickness and the associated interface states on the carrier transport are discussed. (C) 2012 Elsevier B.V. All rights reserved.
Metal-insulator transition characteristics of Mo- and Mn-doped VO2 films fabricated by magnetron cosputtering technique
(2014-06-01)
Liu, Shiu-Jen
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Fang, Hau-Wei
;
Su, Yu-Tai
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Hsieh, Jang-Hsing
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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
Photo-detection characteristics of In-Zn-O/SiOx/n-Si hetero-junctions
(2015-08-01)
Fang, Hau-Wei
;
Hsieh, Tsung-Eong
;
Juang, Jenh-Yih
;
材料科學與工程學系
;
電子物理學系
A layer of indium zinc oxide (IZO) was deposited on the n-type Si substrate clad with a thin thermally grown SiOx layer by pulsed laser deposition to form the semiconductor-insulator-semiconductor (SIS) hetero-junction which exhibits substantial photo-induced responses. Investigation on the IZO layer deposited at various temperatures indicated that IZO film grown at 250 degrees C possesses a resistivity of 4.9 x 10(-4) Omega cm with the transmittance exceeding 80% in the wavelength range between near infrared to ultraviolet light. The photodetection device made of the SIS hetero-junction structure was found to exhibit the photoresponse (R) of 35 AW(-1) and 6.15 AW(-1) with a quick photo-response time less than 80 ms under the illumination of visible light and ultraviolet light, respectively. The underlying mechanism for such a unique characteristic was attributed to the suppression of majority carrier tunneling resulted from the Schottky barrier established at the SIS interfaces. (C) 2015 Elsevier B.V. All rights reserved.
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
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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.