Browsing by Author "Chien, Yun-Shan"

Now showing 1 - 8 of 8

A Novel pH Sensor of Extended-Gate Field-Effect Transistors With Laser-Irradiated Carbon-Nanotube Network
(2012-11-01)
Chien, Yun-Shan
;
Tsai, Wan-Lin
;
Lee, I-Che
;
Chou, Jung-Chuan
;
Cheng, Huang-Chung
The extended-gate field-effect transistors (EGFETs) with only the carbon-nanotube (CNT) thin film as both the sensing membrane and the contact electrode have been demonstrated for the first time to exhibit superior pH sensing characteristics. The continuous-wave laser was necessary to improve the pH sensitivity to be 50.9 mV/pH and the linearity values to be 0.9978 for pH = 3 to pH = 13 wide sensing range, respectively. It implied that the laser energy would unzip the chemically modified multiwalled CNTs (MWCNTs) into numerous graphite slices, resulting in the elevated sensing sites and the improved electrical and sensing properties. Therefore, the laser-irradiated MWCNT network is promising for the applications in the flexible and transparent pH-EGFETs.
Effects of crystallization mechanism on the electrical characteristics of green continuous-wave-laser-crystallized polycrystalline silicon thin film transistors
(2013-07-29)
Chou, Chia-Hsin
;
Lee, I-Che
;
Yang, Po-Yu
;
Hu, Ming-Jhe
;
Wang, Chao-Lung
Thin film transistors (TFTs) with amorphous silicon films crystallized via continuous-wave green laser at a wavelength of 532 nm exhibit very different electrical characteristics in various crystallization regions, corresponding to the Gaussian energy density distribution of the laser beam. In the center region subjected to the highest energy density, the full melting scheme led to the best crystallinity of the polycrystalline silicon film, resulting in the highest field-effect mobility of 500 cm(2) V-1 s(-1). In contrast, the edge region that resulted in solid phase crystallization exhibited the worst mobility of 48 cm 2 V-1 s(-1) for the polycrystalline silicon TFTs. (C) 2013 AIP Publishing LLC.
Growth and Field Emission Characteristics of Pillar-like Carbon Nanotubes Using Co-Ti/Al Co-deposited Catalysts at Low Temperature
(2010)
Chang, C. T.
;
Lee, C. Y.
;
Lin, K. C.
;
Lai, R. L.
;
Tsai, Wan-Lin
In this essay, the pillar-like CNT field emission arrays synthesis with co-deposited catalysts at low temperature (550 degrees C) was proposed. Pillar-like CNT has been successfully synthesized by thermal CVD system. The current density of this proposed pillar like CNTs was as high as 1272 mu A/cm(2) at 6 V/mu m and the turn-on field was 3.6 V/mu m. Additionally, the reliability was more stable as lower than 7% degradation of initial current density.
High-Performance ZnO Thin-Film Transistors with Location-Controlled Crystal Grains Fabricated by Low-Temperature Hydrothermal Method
(2012-07-01)
Yang, Po-Yu
;
Wang, Jyh-Liang
;
Tsai, Wei-Chih
;
Chang, Yu-Cheng
;
Wang, Shui-Jinn
In this paper, high-performance bottom-gate (BG) thin-film transistors (TFTs) with zinc oxide (ZnO) artificially location-controlled lateral grain growth have been prepared via low-temperature hydrothermal method. For the proper design of source/drain structure of ZnO/Ti/Pt thin films, the grains can be laterally grown from the under-cut ZnO beneath the Ti/Pt layer. Consequently, the single one vertical grain boundary perpendicular to the current flow will be produced in the channel region as the grown grains from the source/drain both sides are impinged. As compared with the conventional sputtered ZnO BG-TFTs, the proposed location-controlled hydrothermal ZnO BG-TFTs (W/L = 250 mu m/10 mu m) demonstrated the higher field-effect mobility of 6.09 cm(2)/V.s, lower threshold voltage of 3.67 V, higher on/off current ratio above 10(6), and superior current drivability, reflecting the high-quality ZnO thin films with less grain boundary effect in the channel region.
Improved Field Emission Characteristics with different Electrode Materials by forming process in a Quasi-planar Thin Film Field Emission Diode
(2010-01-01)
Chang, C. T.
;
Hsu, Y. Y.
;
Lin, K. C.
;
Tsai, Wan-Lin
;
Chien, Yun-Shan
The essay was reported the different electrode materials in a quasi-planar thin film field emission diode by different forming process. The forming process causes an increased surface roughness of emitters or reduced the work function of the emitter and results in a higher field enhancement factor, which shows better field emission characteristics. The turn on voltage could from 15 V to 8 V and 6.5V with Co and Pd electrode at the emission current of 100 nA for samples.
Laser-unzipped carbon nanotube based glucose sensor for separated structure of enzyme modified field effect transistor
(2013-12-15)
Tsai, Wan-Lin
;
Chien, Yun-Shan
;
Yang, Po-Yu
;
Lee, I-Che
;
Wang, Kuang-Yu
A glucose sensing film composed of unzipped multiwalled carbon nanotubes (MWCNTs) via continuous-wave laser irradiation is investigated. Some structural defects decorate on MWCNTs after an acid treatment, and the MWCNTs are unzipped into sheet-shaped layers initiated from these defects after the laser irradiation. The laser-irradiated carbon nanotube thin films (CNTFs) possess higher conductance owing to larger contact area, and the side edges of unzipped CNTs could act as sensing sites for hydrogen ions. Thus the laser-irradiated CNTF as a glucose sensing film could achieve a higher sensitivity of 0.302 mV (mg/dl)(-1), equal to 7.55 mV(mg/dl)(-1) per centimeter square, and a larger linearity of 0.9947 than the as-sprayed one. Moreover, the fully low-temperature processes of this work also reveal the potentials for flexible and disposable biosensors. (C) 2013 Published by Elsevier B.V.
The mechanism of the surface morphology transformation for the carbon nanotube thin film irradiated via excimer laser
(2013-05-06)
Chien, Yun-Shan
;
Lee, I-Che
;
Yang, Po-Yu
;
Wang, Chao-Lung
;
Tsai, Wan-Lin
In this paper, the surface morphology transformation of the sprayed carbon nanotube (CNT) thin film irradiated with the excimer laser has been systematically investigated. Under the excimer-laser irradiation, two phenomena, including the annealing and ablation effects, were found to be dependent on the incident laser energy and overlapping ratios. Moreover, the extremely high protrusions would be produced in the interface between the annealing and ablation regions. The mechanism of the CNT thin film under the excimer laser irradiation was, therefore, proposed to derive the surface morphology modifications and the further reinforced crystallinity with proper laser energy densities and overlapping ratios. (C) 2013 AIP Publishing LLC.
The pH Sensing Characteristics of the Extended-Gate Field-Effect Transistors of Multi-Walled Carbon-Nanotube Thin Film Using Low-Temperature Ultrasonic Spray Method
(2012-07-01)
Chien, Yun-Shan
;
Yang, Po-Yu
;
Tsai, Wan-Lin
;
Li, Yu-Ren
;
Chou, Chia-Hsin
A novel, simple and low-temperature ultrasonic spray method was developed to fabricate the multi-walled carbon-nanotubes (MWCNTs) based extended-gate field-effect transistors (EGFETs) as the pH sensor. With an acid-treated process, the chemically functionalized two-dimensional MWCNT network could provide plenty of functional groups which exhibit hydrophilic property and serve as hydrogen sensing sites. For the first time, the EGFET using a MWCNT structure could achieve a wide sensing rage from pH = 1 to pH = 13. Furthermore, the pH sensitivity and linearity values of the CNT pH-EGFET devices were enhanced to 51.74 mV/pH and 0.9948 from pH = 1 to pH = 13 while the sprayed deposition reached 50 times. The sensing properties of hydrogen and hydroxyl ions show significantly dependent on the sprayed deposition times, morphologies, crystalline and chemical bonding of acid-treated MWCNT. These results demonstrate that the MWCNT-EGFETs are very promising for the applications in the pH and biomedical sensors.