Browsing by Author "Tsai, C. C."

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Controlled density growth of carbon nanotubes and its improvement on field emission properties
(2004)
Juan, C. P.
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Tsai, C. C.
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Chen, K. J.
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Hong, W. K.
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Lin, K. C.
The density distribution of the CNTs is one of the crucial parameters for the field emission property of CNTs.We use an inactive thin film layer that was deposited on the catalyst to effectively control the density of the CNTs. The results showed the improved field emission property could be obtained with a thin SiO layer on the catalyst layer as the precursor. For the 3.5 nm Fe and 3.5 nm SiO on 3.5 nm Fe as the catalyst, the turn-on field can be reduced from 3.7 V/ mu m. to 2.2 V/ mu m and the field emission current density increased from 2.6x 10(-8) A/cm(2) to 2.4x 10(-4) A/cm(2) when the applied field was 4 V/mu m. The extremely low turn-on field of 1.3 V/ mu m was also discovered for the CNTs grown with the precursor contained 1.5 nm SiO on 1.5 nm Fe; the extremely high emission current density of 4x 10(-2) A/cm(2) was also achieved under the low electric field of 3.5 V/ mu m.
Enhanced spectral response by silicon nitride index matching layer in amorphous silicon thin-film solar cells
(2012-09-01)
Hsu, C. H.
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Lin, Y. P.
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Hsu, H. J.
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Tsai, C. C.
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光電工程學系
We employed the low temperature hydrogenated amorphous silicon nitride (a-SiNx:H) prepared by plasma-enhanced chemical vapor deposition as a refractive index (n) matching layers in a silicon-based thin-film solar cell between glass (n = 1.5) and the transparent conducting oxide (n = 2). By varying the stoichiometry, refractive index and thickness of the a-SiNx:H layers, we enhanced the spectral response and efficiency of the hydrogenated amorphous silicon thin-film solar cells. The refractive index of a-SiNx:H was reduced from 2.32 to 1.78. Optimizing the a-SiNx:H thickness to 80 nm increased the J(SC) from 8.3 to 9.8 mA/cm(2) and the corresponding cell efficiency increased from 4.5 to 53%, as compared to the cell without the a-SiNx:H index-matching layer on planar substrate. The a-SiNx:H layers with graded refractive indices were effective for enhancing the cell performance. (C) 2012 Elsevier B.V. All rights reserved.
High-performance polycrystalline silicon thin-film transistors with oxidenitride-oxide gate dielectric and multiple nanowire channels
(2006-11-25)
Chen, Shih-Ching
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Chang, Ting-Chang
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Liu, Po-Tsun
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Wu, Y. C.
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Tsai, C. C.
This work presents a method to enhance the performance of polycrystalline silicon thin film transistors (poly-Si TFTs) by using an oxide-nitride-oxide (ONO) gate dielectric and the multiple nanowire channels structure. Experimental results indicate that the performance of the device was enhanced by using the ONO multilayer, because the ONO gate dielectric constant is increased compared to the conventional oxide gate dielectric. Additionally, the TFTs with a ten nanowire channel structure (NW-TFTs) have superior electrical characteristics compared to other TFTs. This is because a structure with more corners and a shorter radius has better gate control due to the corner effect. (c) 2006 Elsevier B.V. All rights reserved.
Influence of Hydrogen on the Germanium Incorporation in a-Si1-xGex:H for Thin-Film Solar Cell Application
(2010-01-01)
Wang, C. M.
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Huang, Y. T.
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Yen, K. H.
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Hsu, H. J.
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Hsu, C. H.
In this work, we examined the Ge incorporation and the accompanied defect formation during PECVD deposition of hydrogenated amorphous silicon-germanium alloys (a-Si1-xGex:H). In particular, we studied the effect of hydrogen on film growth, defect formation, Ge and Si incorporation efficiencies, and the H-bonding configuration. Our results indicate that hydrogen has a strong effect on improving the a-Si1-xGex:H film quality and the Ge incorporation in a-Si1-xGex:H. With adequate hydrogen dilution, the a-Si1-xGex:H thin-film quality significantly improved. However, excessive hydrogen dilution degraded the film properties. A number of analytical tools were employed, including FTIR, XPS, UV-Visible spectroscopy, photoconductivity, etc. The a-Si1-xGex:H material having 24% Ge content and a bangap of 1.61ev produced the solar cell with a conversion efficiency of 7.07%.
Investigation of Cat-CVD amorphous silicon film properties under high catalyzer temperature
(2010)
Yen, K. H.
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Nishizaki, S.
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Ohdaira, K.
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Matsumura, H.
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Huang, Y. T.
In this study, we investigated the a-Si films which were deposited by Cat-CVD in the higher catalyzer temperature (T(cat)) regime. We studied the influence of high T(cat) on amorphous silicon (a-Si:H) thin-film properties. The information on a-Si-H bonding configuration was obtained by Fourier Transform Infrared Spectroscopy (FTIR). The film defect density was investigated by the electron spin resonance (ESR) as a function of T(cat), the distance between catalyzer and substrate (D(cs)), and the deposition pressure (P). (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Optimization of the absorber layer for a-Si:H and a-Si1-xGex:H single-junction solar cells
(2011)
Tsai, C. C.
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Hsu, C. H.
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Hsu, H. J.
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Cheng, P. H.
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Wang, C. M.
This paper focuses on the optimization of the absorber layers in single-junction a-Si:H and a-Si1-xGex:H solar cells. For a-Si:H thin-film solar cells, we have found the electrode-to-substrate (E/S) spacing is an important parameter. By optimizing the E/S spacing, the cell effi-ciency was improved from 7.62% to 8.70% due to an improvement in material quality and JSC. For a-Si1-xGex:H solar cells, by optimizing the Ge-content, the microstructure parameter and the graded bandgap, we were able to improve the cell efficiency to 8.15%. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Study of Crystallinity in mu c-Si: H Films Deposited by Cat-CVD for Thin Film Solar Cell Applications
(2010-01-01)
Hsu, C. H.
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Hsu, Y. P.
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Yao, F. H.
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Huang, Y. T.
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Tsai, C. C.
The crystallinity of the hydrogenated microcrystalline silicon (mu c-Si:H) film was known to influence the solar cell efficiency greatly. Also hydrogen was found to play a critical role in controlling the crystallinity. Instead of employing conventional plasma deposition techniques, this work focused on using catalytic chemical vapor deposition (Cat-CVD) to study the effect of hydrogen dilution and the filament-to-substrate distance on the crystallinity, deposition rate, microstructure factor and electrical property of the mu c-Si: H film. We found that the substrate material and structure can affect the crystallinity of the mu c-Si: H film and the incubation effect. Comparing bare glass, TCO-coated glass, a-Si: H-coated glass and mu c-Si: H-coated glass, the microcrystalline phase grows the fastest onto mu c-Si: H surface, but the slowest onto a-Si: H surface. Surprisingly, the template effect lasted for more than a thousand atomic layers of silicon.
The Impact of the Shallow-Trench Isolation Effect on Flicker Noise of Source Follower MOSFETs in a CMOS Image Sensor
(2018-06-01)
Fan, C. C.
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Chiu, Y. C.
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Liu, C.
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Lai, W. W.
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Cheng, C. H.
The flicker noise of source follower transistors is the dominant noise source in image sensors. This paper reports a systematic study of the shallow trench isolation effect in transistors with different sizes under high temperature conditions that correspond to the quantity of empty defect sites. The effects of shallow trench isolation sidewall defects on flicker noise characteristics are investigated. In addition, the low-frequency noise and subthreshold swing degrade simultaneously in accordance to the device gate width scaling. Both serious subthreshold leakage and considerable noise can be attributed to the high trap density near the STI edge. Consequently, we propose a coincidental relationship between the noise level and the subthreshold characteristic; its trend is identical to the experiments and simulation results.
UV excited flat lighting (UFL) system for LCD-TV backlight application
(2008)
Huang, Hsin-Tao
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Hung, Chien-Hsiang
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Huang, Yi-Pai
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Tien, Chung-Hao
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Tsai, C. C.
Different to the conventional visible-CCFL backlight, UV excited flat lighting (UFL) applies UV-CCFL to irradiate 254 nm wavelengths to excite extrinsic phosphor layer to perform uniform and flat lighting for LCD-TV applications. UFL can yield longer life time due to less phosphor damage. Additionally, high color rendering, minor color deviation, wider FWHM (Fall width at half maximum) angle, and better lamp mura relaxation, were demonstrated to achieve a high quality display with slim backlight module.