Browsing by Author "Wang, Chih"

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Anisotropic optical transmission of femtosecond laser induced periodic surface nanostructures on indium-tin-oxide films
(2012-09-03)
Wang, Chih
;
Wang, Hsuan-I
;
Luo, Chih-Wei
;
Leu, Jihperng
;
材料科學與工程學系
Two types of periodic nanostructures, self-organized nanodots and nanolines, were fabricated on the surfaces of indium-tin-oxide (ITO) films using femtosecond laser pulse irradiation. Multiple periodicities (approximately 800 nm and 400 nm) were clearly observed on the ITO films with nanodot and nanoline structures and were identified using two-dimensional Fourier transformation patterns. Both nanostructures show the anisotropic transmission characteristics in the visible range, which are strongly correlated with the geometry and the metallic content of the laser-induced nanostructures. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4751983]
Effects of CF(4) plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
;
Lai, Po-Cheng
;
Syu, Shu Hao
;
Leu, Jihperng
;
材料科學與工程學系
We studied the effects of CF(4) plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF(4) plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF(4) plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF(4) plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.
Effects of CF4 plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
;
Lai, Po-Cheng
;
Syu, Shu Hao
;
Leu, Jihperng
;
材料科學與工程學系
We studied the effects of CF4 plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF4 plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF4 plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF4 plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.
Structural and morphological transformations of TiO2 nanotube arrays induced by excimer laser treatment
(2012-02-29)
Hsu, Ming-Yi
;
Nguyen Van Thang
;
Wang, Chih
;
Leu, Jihperng
;
材料科學與工程學系
The structural and morphological transformations of TiO2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 degrees C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85 degrees was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. (c) 2011 Elsevier B.V. All rights reserved.
Superior local conductivity in self-organized nanodots on indium-tin-oxide films induced by femtosecond laser pulses
(2011-11-21)
Wang, Chih
;
Wang, Hsuan-I
;
Tang, Wei-Tsung
;
Luo, Chih-Wei
;
Kobayashi, Takayoshi
Large-area surface ripple structures of indium-tin-oxide films, composed of self-organized nanodots, were induced by femtosecond laser pulses, without scanning. The multi-periodic spacing (similar to 800 nm, similar to 400 nm and similar to 200 nm) was observed in the laser-induced ripple of ITO films. The local conductivity of ITO films is significantly higher, by approximately 30 times, than that of the as-deposited ITO films, due to the formation of these nanodots. Such a significant change can be ascribed to the formation of indium metal-like clusters, which appear as budges of similar to 5 nm height, due to an effective volume increase after breaking the In-O to form In-In bonding. (C) 2011 Optical Society of America