Browsing by Author "Wu, Hung-Chi"

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Effect of Mg Doping on the Electrical Characteristics of High Performance IGZO Thin Film Transistors
(2014)
Wu, Hung-Chi
;
Liu, Tung-Sheng
;
Chien, Chao-Hsin
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this work, we report that the electrical characteristics of Indium-Gallium-Zinc-Oxide Thin Film Transistors (IGZO-TFTs) can be improved by Mg doping in the IGZO layer. Several composite IGZO/Mg-doped IGZO channel structures were employed. With appropriate Mg-doped IGZO thickness, the electrical properties such as mobility, subthreshold swing (S.S.) and on/off ratio can be significantly improved by Mg doping. Mg doping in IGZO layer can stabilize device performance whatever the device is stressed under positive gate bias or negative gate bias with illumination. By X-ray photoelectron (XPS) analysis, we observe the presence of Mg can change the oxygen bonding states and influence the properties of IGZO layer. The atomic percentage of Mg in the IGZO layer is about 6.53%. As a result, Mg doping is a useful method to enhance the performance and stability of IGZO-TFTs. (C) 2013 The Electrochemical Society. All rights reserved.
Effect of passivation layer on InGaZnO thin-film transistors with hybrid silver nanowires as source and drain electrodes
(2015-08-01)
Yu, Chien-Hsien
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Wu, Hung-Chi
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Chien, Chao-Hsin
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
InGaZnO (IGZO) thin-film transistors (TFTs) with hybrid silver nanowires (hybrid-AgNWs) as the source and drain electrodes exhibit superior performance according to the on/off current ratio (approximate to 10(6)), subthreshold swing (SS) (367 mV/decade), and mobility (15.6 cm(2) V-1 s(-1)). The transfer and output characteristics of nanowire-based electrodes are comparable with those of titanium electrodes. The devices are fabricated on a plastic substrate and are highly transparent (>70%) and flexible. The device performance is severely degraded during operation in air, especially under high humidity conditions, and progressive deterioration resulting from water molecule diffusion leads to a high current density when the device is swept. Hence, introducing a passivation layer on the hybrid-AgNW electrodes is imperative. (C) 2015 The Japan Society of Applied Physics
Electron Field Emission Properties of Nanomaterials on Rough Silicon Rods
(2010-01-14)
Wu, Hung-Chi
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Tsai, Tsung-Yen
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Chu, Fu-Hsuan
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Tai, Nyan-Hwa
;
Lin, Heh-Nan
Highly porous, individually separated, and vertically aligned rough silicon rods (r-SiRs) were formed via a modified electroless metal deposition (EMD) approach. Despite inheriting the length of crowded silicon nanowires (NWs) obtained by the conventionally adopted EMD method, the r-SiRs are distributed sparsely, subsequently forming an excellent field emitter substrate. The electron field emission (EFE) of carbon nanotubes (CNTs) grown on r-SiRs can be turned on at (E(0))(CNTs/r-SiRs) = 2.3 V/mu m, yielding a high EFE current density, (J(c))(CNTs/r-SiR) = 3.7 mA/cm(2) in an applied field of 5.1 V/mu m, Additionally, a cactuslike structure consisting of zinc oxide NWs on r-SiRs can be turned on at 2.9 V/mu m. The absence of a high-temperature or expensive photolithographic process makes r-SiRs a promising alternative as a silicon base field emitter substrate.
High performance InGaZnO thin film transistor with InGaZnO source and drain electrodes
(2013-02-11)
Wu, Hung-Chi
;
Chien, Chao-Hsin
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work demonstrates In-Ga-Zn-O (IGZO) as source and drain electrodes in IGZO-thin film transistors (TFTs). The fabricated TFT depicts excellent electrical properties; its mobility is 18.02 (cm(2)/V s), threshold voltage (Vth) is 0.3 (V), on/off ratio is 1.63 x 10(8) and subthreshold swing (S. S.) is 239 (mV/decade). We find using rapid thermal annealing treatment can convert IGZO into an effective conductor, and the transparency of IGZO remained almost unchanged. We also find sufficient thermal budget is needed for getting stable transfer curve and output characteristic; otherwise, current fluctuation in on-state can be easily observed. With IGZO electrodes, fully transparent IGZO-TFTs can be thus realized on a glass substrate. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789997]
Highly Transparent, High-Performance IGZO-TFTs Using the Selective Formation of IGZO Source and Drain Electrodes
(2014-06-01)
Wu, Hung-Chi
;
Chien, Chao-Hsin
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, high-performance, highly transparent amorphous InGaZnO (IGZO) thin-film transistors (TFTs) with IGZO source/drain electrodes were fabricated. Rapid thermal annealing treatment effectively converted IGZO from a semiconductor into a conductor. Using a patterned SiO2 capping layer, highly transparent IGZO-TFTs with selectively formed IGZO electrodes were fabricated on a glass substrate. The mobility of the fabricated IGZO-TFT was 8.3 cm(2)/V s, ON/OFF ratio was 3.1 x 10(6), and subthreshold swing was 0.44 V/decade. Thus, the proposed scheme provides a simple and practical method of fabricating high-performance, highly transparent IGZO TFTs.
Improving Electrical Properties of Bottom-Gate Poly(3-Hexylthiophene) Thin-Film Transistor Using CF4 Plasma Treatment
(2013-04-01)
Wu, Hung-Chi
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Chien, Chao-Hsin
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, the effect of CF4 plasma treatment on poly(3-hexylthiophene)-based organic thin-film transistors has been investigated. It was found that CF4 plasma treatment on the source/drain electrode can reduce contact resistance and increase mobility. The CF4 plasma treatment can increase the mobility from 0.0021 to 0.0102 cm(2)/V . s and decrease the contact resistance by about 70%. Moreover, the CF4 plasma treatment is compatible with the bottom-gate bottom-contact structure without degrading the SiO2 layer.
Nearly fully transparent InGaZnO thin film transistors with Mo-InGaZnO electrodes
(2014-01-01)
Wu, Hung-Chi
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Chien, Chao-Hsin
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, we demonstrate high performance and highly transparent InGaZnO thin film transistors (IGZO-TFTs) with nearly metal-free Mo doped IGZO source/drain (S/D) electrodes by co-sputtering. The electrical parameters such as filed effect mobility, on/off ratio and subthreshold swing are 15.9 cm(2)/V sec, 3.82x10(7) and 300 mV/decade, respectively. The electrical performance and reliability of the IGZO-TFTs with Mo-IGZO S/D electrodes are comparable with the conventional IGZO-TFTs with Mo electrodes. Besides, the transparency is remarkably improved. With the optimized condition, the transmittance of the IGZO-TFTs with Mo-IGZO S/D electrodes can be > 70%. From XPS material analysis, the addition of Mo can change the oxygen bonding states in IGZO, which may be the reason for the observed conductor behavior of IGZO. Hence, the formation of Mo-IGZO S/D electrodes with co-sputtering is a simple, cost effective and low temperature method for achieving fully transparent IGZO-TFTs with high electrical performance and well reliability.
One-dimensional germanium nanostructures-formation and their electron field emission properties
(2010-11-12)
Wu, Hung-Chi
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Hou, Te-Chien
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Chueh, Yu-Lun
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Chen, Lih-Juann
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Chiu, Hsin-Tien
Ge nanostructures were synthesized by reduction of GeO(2) in H(2) atmosphere at various temperatures. Entangled and straight Ge nanowires with oxide shells were grown at high temperatures. Ge nanowires with various numbers of nodules were obtained at low temperatures. Ge nanowires without nodules exhibited remarkable field emission properties with a turn-on field of 4.6 V mu m(-1) and field enhancement factor of 1242.
One-dimensional germanium nanostructures-formation and their electron field emission properties
(2010-11-12)
Wu, Hung-Chi
;
Hou, Te-Chien
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Chueh, Yu-Lun
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Chen, Lih-Juann
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Chiu, Hsin-Tien
Ge nanostructures were synthesized by reduction of GeO(2) in H(2) atmosphere at various temperatures. Entangled and straight Ge nanowires with oxide shells were grown at high temperatures. Ge nanowires with various numbers of nodules were obtained at low temperatures. Ge nanowires without nodules exhibited remarkable field emission properties with a turn-on field of 4.6 V mu m(-1) and field enhancement factor of 1242.
One-Step Ge/Si Epitaxial Growth
(2011-07-01)
Wu, Hung-Chi
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Lin, Bi-Hsuan
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Chen, Huang-Chin
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Chen, Po-Chin
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Sheu, Hwo-Shuenn
Fabricating a low-cost virtual germanium (Ge) template by epitaxial growth of Ge films on silicon wafer with a Ge(x)Si(1-x) (0 < x < 1) graded buffer layer was demonstrated through a facile chemical vapor deposition method in one step by decomposing a hazardousless GeO(2) powder under hydrogen atmosphere without ultra-high vacuum condition and then depositing in a low-temperature region. X-ray diffraction analysis shows that the Ge film with an epitaxial relationship is along the in-plane direction of Si. The successful growth of epitaxial Ge films on Si substrate demonstrates the feasibility of integrating various functional devices on the Ge/Si substrates.
Silicon Rice-Straw Array Emitters and Their Superior Electron Field Emission
(2010-11-01)
Wu, Hung-Chi
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Tsai, Hung-Yin
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Chiu, Hsin-Tien
;
Lee, Chi-Young
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應用化學系
Free standing and vertically aligned silicon rice-straw like array emitters were fabricated by modified electroless metal deposition (EMD), using HFH(2)C(2) as an erching solution to reduce the emitter density and to make the emitter end of the formed silicon rice-straw arrays shaper than those formed by conventional EMD. These silicon rice-straw array emitters can be turned on at E(0) = 4.7 V/mu m, yielding an EFE (electron field emission) current density of f(c) = 139 mu A/cm(2) in an applied field of 12.8 V/mu m. According to a simple simulation, the excellent EFE performance of the silicon rice-straw array emitters originates in not only the favorable distribution of emitter arrays, but also the shape of the emitter apexes. The modified-EMD method is easily scaled up without expensive equipment, so silicon rice-straw array emitters are a promising alternative to silicon-based field emitters.
Stacked Silicon Nanowires with Improved Field Enhancement Factor
(2010-02-01)
Tzeng, Yu-Fen
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Wu, Hung-Chi
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Sheng, Pei-Sun
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Tai, Nyan-Hwa
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Chiu, Hsin Tien
This work describes newly structured stacked silicon nanowires (s-SiNWs), consisting of nanosized silicon wires on top of silicon microrods (SiMRs) and exhibiting pronouncedly superior electron held emission (EFE) characteristics to the conventional SiNWs, by using a two-step electroless metal deposition process. Experimental results indicate that for these s-SiNWs, the electrostatic "screen effect" is markedly suppressed and the held enhancement factor (beta-value) is significantly increased ((beta)(s-SiNWs) = 2533). Additionally, the turn-on held (Eo) for triggering the EFE process is reduced to a level comparable with that of carbon nanotubes, viz. (E(0))(s-SiNWs) = 2.0 V/mu m. This simple and robust modified electroless metal deposition approach does not require either a high temperature or an expensive photolithographic process and possesses great potential for applications.
The evolution of Ge nanostructures growth on silicon substrate by reduction of GeO2
(2012)
Wu, Hung-Chi
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Chiu, Hsin-Tien
;
Lee, Chi-Young
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應用化學系
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Department of Applied Chemistry
Various shaped and sized Ge nanostructures were obtained by reducing GeO2 powder under a H-2 atmosphere in a high-temperature tubular furnace. At a high depositing temperature region, crystalline Ge film was epitaxially grown on a silicon substrate. Jellyfish-like Ge/SiO(2)NWs composite structures were obtained next to germanium epitaxial film grown by Ge-catalyzed vapor-liquid-solid phase segregation mechanism. In addition, at the lower depositing temperature zones, Ge nanowires with various morphologies were formed owing to the temperature and concentration gradient by oxide-assisted vapor-solid mechanism and Ostwald ripening.