Browsing by Author "Chang, Che-Lun"

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A simple Spacer technique to fabricate poly-Si TFTs with 50-nm nanowire channels
(2007-11-01)
Chang, Chia-Wen
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Deng, Chih-Kang
;
Chang, Hong-Ren
;
Chang, Che-Lun
;
Lei, Tan-Fu
In this letter, polycrystalline-silicon thin-film transistors (poly-Si TFTs) with 50-nm nanowire (NW) channels, which are fabricated without advanced photolithography by using a side-wall spacer-formation technique, are proposed for the first time. Because the polygate electrode is perpendicularly across poly-Si NW channels to form a trigatelike structure, the proposed poly-Si NW TFT owns outstanding gate controllability. In summary, a simple and low-cost scheme is proposed to fabricate high-performance poly-Si NW TFT suitable for future display manufacturing and practical applications.
An Inflatable and Wearable Wireless System for Making 32-Channel Electroencephalogram Measurements
(2016-07)
Yu, Yi-Hsin
;
Lu, Shao-Wei
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Chuang, Chun-Hsiang
;
King, Jung-Tai
;
Chang, Che-Lun
Potable electroencephalography (EEG) devices have become critical for important research. They have various applications, such as in brain-computer interfaces (BCI). Numerous recent investigations have focused on the development of dry sensors, but few concern the simultaneous attachment of high-density dry sensors to different regions of the scalp to receive qualified EEG signals from hairy sites. An inflatable and wearable wireless 32-channel EEG device was designed, prototyped, and experimentally validated for making EEG signal measurements; it incorporates spring-loaded dry sensors and a novel gasbag design to solve the problem of interference by hair. The cap is ventilated and incorporates a circuit board and battery with a high-tolerance wireless (Bluetooth) protocol and low power consumption characteristics. The proposed system provides a 500/250 Hz sampling rate, and 24 bit EEG data to meet the BCI system data requirement. Experimental results prove that the proposed EEG system is effective in measuring audio event-related potential, measuring visual event-related potential, and rapid serial visual presentation. Results of this work demonstrate that the proposed EEG cap system performs well in making EEG measurements and is feasible for practical applications.
Enhanced performance and reliability for solid phase crystallized poly-Si TFTs with argon ion implantation
(2007)
Chang, Chia-Wen
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Chang, Che-Lun
;
Luo, Wun-Chen
;
Lee, Jam-Wem
;
Lei, Tan-Fu
Performance and reliability improvement for polycrystalline silicon thin-film transistors (poly-Si TFrs) with Argon ion implantation are proposed for the first time. By adopting this novel surface -nucleation solid -phase-cry stallization scheme, not only the grain size of poly-Si can be increased but also the intragranular defects can be suppressed effectively. Therefore, a high quality of poly-Si film in channel with better crystallinity is formed. Argon-implanted TFrs have been successfully fabricated and the experimental results demonstrate a superior field-effect mobility of 46. 06 cm(2)/VS, a fewer grain boundary trap density of 3.44 x 10(12) cm(-2) than those of conventional TFrs. The novel proposed structure is a very promising candidate for the future high-performance large-area device applications.
Enhanced performance and reliability for solid-phase crystallized poly-Si TFTs with argon ion implantation (vol 154, pg J375, 2007)
(2008)
Chang, Chia-Wen
;
Deng, Chih-Kang
;
Chang, Che-Lun
;
Lei, Tan-Fu
;
電子工程學系及電子研究所
High-performance nanowire TFTs with metal-induced lateral crystallized poly-Si channels
(2008-05-01)
Chang, Chia-Wen
;
Chen, Szu-Fen
;
Chang, Che-Lun
;
Deng, Chih-Kang
;
Huang, Jiun-Jia
High-performance poly-Si thin-film transistors (TFTs) with 50-nm nanowire (NW) channels fabricated by integrating a simple spacer formation scheme and metal-induced-lateral-crystallization (MILC) technique are proposed. By using the sidewall spacer formation scheme, the NW channels with nanometer-scale feature sizes can be easily fabricated, exhibiting superior channel controllability through the triple-gate structure. In employing the MILC technique, the grain crystallinity of NW channels is significantly superior to that formed by the solid-phase-crystallization (SPC) technique. Therefore, the MILC NW TFT exhibits greatly improved electrical performances, including lower threshold voltage, steeper subthreshold swing, and higher field-effect mobility, as compared to those of the SPC NW TFT. Moreover, the superior threshold-voltage rolloff characteristics of MILC NW TFT are also demonstrated.
High-performance solid-phase crystallized polycrystalline silicon thin-film transistors with floating-channel structure
(2008-04-01)
Chang, Chia-Wen
;
Deng, Chih-Kang
;
Chang, Che-Lun
;
Liao, Ta-Chuan
;
Lei, Tan-Fu
High-performance solid-phase crystallized polycrystalline silicon thin-film transistors with a floating-channel active region (FC poly-Si TFTs) are proposed in this study. A high-quality poly-Si channel film accompanied by a larger grain size and fewer microstructural defects could be obtained. Compared with the conventional poly-Si TFTs (CN poly-Si TFTs), the fabricated FC poly-Si TFTs exhibit superior electrical characteristics, including lower threshold voltage, higher field-effect mobility, and lower trap state density. These electrical performance improvements could be attributed to the fact that the a-Si film with a floating-channel structure can relieve the stress generated from the crystallization process accompanying the trap state density reduction and grain size enhancement. In addition, the FC poly-Si TFTs also exhibit improved hot-carrier stress immunity due to the reduced weak Si-H bonds from fewer grain boundaries in the poly-Si channel. Therefore, the proposed FC poly-Si TFTs can be easily fabricated by conventional solid-phase crystallization, and suitable for future high-performance flat-panel display applications.
Improvement of electrical characteristics for novel process-compatible floating channel solid-phase crystallized poly-Si TFTs
(2007)
Chang, Chia-Wen
;
Chang, Che-Lun
;
Lee, Jam-Wem
;
Lei, Tan-Fu
;
電子工程學系及電子研究所
High-performance polycrystalline-silicon thin-film transistors (poly-Si TFTs) with floating channel solid-phase crystallization are proposed for the first time. By adopting this novel crystallization scheme, a better crystalline poly-Si film can be obtained in the suspended channel film. Poly-Si TFTs with this novel floating channel structure have been successfully fabricated and the experimental results demonstrate a superior electrical performance and reliability.
New Flexible Silicone-Based EEG Dry Sensor Material Compositions Exhibiting Improvements in Lifespan, Conductivity, and Reliability
(2016-11-01)
Yu, Yi-Hsin
;
Chen, Shih-Hsun
;
Chang, Che-Lun
;
Lin, Chin-Teng
;
Hairston, W. David
This study investigates alternative material compositions for flexible silicone-based dry electroencephalography (EEG) electrodes to improve the performance lifespan while maintaining high-fidelity transmission of EEG signals. Electrode materials were fabricated with varying concentrations of silver-coated silica and silver flakes to evaluate their electrical, mechanical, and EEG transmission performance. Scanning electron microscope (SEM) analysis of the initial electrode development identified some weak points in the sensors' construction, including particle pull-out and ablation of the silver coating on the silica filler. The newly-developed sensor materials achieved significant improvement in EEG measurements while maintaining the advantages of previous silicone-based electrodes, including flexibility and non-toxicity. The experimental results indicated that the proposed electrodes maintained suitable performance even after exposure to temperature fluctuations, 85% relative humidity, and enhanced corrosion conditions demonstrating improvements in the environmental stability. Fabricated flat (forehead) and acicular (hairy sites) electrodes composed of the optimum identified formulation exhibited low impedance and reliable EEG measurement; some initial human experiments demonstrate the feasibility of using these silicone-based electrodes for typical lab data collection applications.
Performance and reliability improvement for poly-Si TFTs using fluorinated silicate glass inter-layer-dielectric passivation
(2007)
Chang, Chia-Wen
;
Wu, Tin-Wei
;
Wang, Tong-Yi
;
Chang, Che-Lun
;
Lee, Jam-Wem
Polycrystalline silicon thin-film transistors (poly-Si TFTs) with fluorinated silicate glass (FSG) inter-layer dielectric (ILD) passivation layer were proposed and demonstrated in this study. The presence of outdiffused fluorine atoms from FSG layer can eliminate Si dangling bonds at the grain boundaries near the drain side. The proposed short channel poly-Si TFTs with FSG ILD passivation have a slightly improved on-current, a obviously suppressed serious kink-effect, and a remarkably reduced off-leakage current than those with undoped SiO2 ILD passivation. Furthermore, the incorporation of fluorine atoms in poly-Si film can also form stronger Si-F bonds at drain side to enhance the immunity to hot carrier stress. Besides, the proposed TFTs structure is simple, low cost, and process compatible with present TFTs manufacturing technology.