Browsing by Author "Yang, Chih-Chiang"

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Electron Emission Enhanced Properties of Gold Nanoparticle-Decorated ZnO Nanosheets Grown at Room Temperature
(2018-12-01)
Wang, Zi-Hao
;
Yang, Chih-Chiang
;
Yu, Hsin-Chieh
;
Peng, Yu-Ming
;
Su, Yan-Kuin
In this study, gold nanoparticles were adsorbed on glass nanosheets (NSs) grown on the surface of glass substrates with aqueous solutions at room temperature. The diameter and length of gold coater ZnO NSs are approximately 50 nm and 0.9 mu m, respectively. The Au-decorated ZnO NS grown at room temperature is structurally uniform and has a good orientation of the wurtzite structure. The turn-on electric fields of ZnO and Au-decorated ZnO nanosheets were 6.04 and 4.91 V/mu m, respectively. The field-enhancement factors were 2507 and 9298, respectively. Results showed that the Au-decorated ZnO NS has enhanced field-emission properties. In addition, due to the reduced size of the protruding Au nanoparticles, the number of emitting sites increases.
Electron Field Emission Enhancement Based on Al-Doped ZnO Nanorod Arrays With UV Exposure
(2018-01-01)
Wang, Zi-Hao
;
Yang, Chih-Chiang
;
Yu, Hsin-Chieh
;
Yeh, Hsin-Ting
;
Peng, Yu-Ming
In this paper, Al-doped ZnO nanorods (AZO NRs) were successfully applied on glass substrates through hydrothermal synthesis growth with a fabrication field-emission (FE) device. The enhanced FE properties of AZO NRs were measured. The turn-on fields were reduced by 2.35 and 1.51 V/mu m in the dark and under UV light, and the enhanced field enhancement factors (beta) were 5708 and 10137, respectively. Results show that the FE performances of AZO NRs were enhanced by the combined effect of increased carrier concentration and UV light illumination.
Impact of Oxygen Vacancy on the Photo-Electrical Properties of In2O3-Based Thin-Film Transistor by Doping Ga
(2019-03-01)
Chen, Kuan-Yu
;
Yang, Chih-Chiang
;
Su, Yan-Kuin
;
Wang, Zi-Hao
;
Yu, Hsin-Chieh
In this study, amorphous indium gallium oxide thin-film transistors (IGO TFTs) were fabricated by co-sputtering. Three samples with different deposition powers of the In2O3 target, namely, sample A with 50 W deposition power, sample B with 60 W deposition power, and sample C with 70 W deposition power, were investigated. The device performance revealed that oxygen vacancies are strongly dependent on indium content. However, when the deposition power of the In2O3 target increased, the number of oxygen vacancies, which act as charge carriers to improve the device performance, increased. The best performance was recorded at a threshold voltage of 1.1 V, on-off current ratio of 4.5 x 10(6), and subthreshold swing of 3.82 V/dec in sample B. Meanwhile, the optical properties of sample B included a responsivity of 0.16 A/W and excellent ultraviolet-to-visible rejection ratio of 8 x 10(4). IGO TFTs may act as photodetectors according to the results obtained for optical properties.
Low-Frequency Noise Performance of Al-Doped ZnO Nanorod Photosensors by a Low-Temperature Hydrothermal Method
(2017-08-01)
Wang, Zi-Hao
;
Yu, Hsin-Chieh
;
Yang, Chih-Chiang
;
Yeh, Hsin-Ting
;
Su, Yan-Kuin
In this paper, we developed a simple hydrothermal method to synthesize vertically aligned ZnO:Al nanorods (NRs) to fabricate a UV photodetector (PD) on a seed layer/glass substrate. The photo-to-dark current ratio of the ZnO: Al NR PD was approximately 1.4 x 10(3) under 1-V bias and UV light irradiation (380 nm). The calculated responsivity of the fabricated PD was 181 A . W-1, and the UV-to-visible rejection ratio of the PD at 1-V applied bias was 1.51 x 10(3). In addition, flicker noise dominated the noise of the ZnO: Al NR PD. The noise-equivalent power and normalized detectivity of the ZnO:Al NR PD were 1.17 x 10(-11) W and 4.03 x 10(12) cm . Hz(0.5)W(-1), respectively.
Random Early Detection Web Servers for Dynamic Load Balancing
(2009)
Yang, Chih-Chiang
;
Chen, Chien
;
Chen, Jing-Ying
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資訊工程學系
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Department of Computer Science
Modern Web-server systems use multiple servers to handle an increased user demand. Such systems need effective methods to spread the load among web servers evenly in order to keep web server utilization high while providing sufficient quality of service for end users. In conventional DNS-based load balancing architecture, a Doman Name Server (DNS) dispatches requests to web servers based on their load status. Because web servers need to inform the DNS server about their load status from time to time, a so-called load buffer range is often employed to reduce the update frequency. Without care, however, using a load buffer range may result in load oscillation among web servers. To address this problem, we propose a Random Early Detection (RED) method with the intuition that the probability for a web server to become overloaded in near future is directly proportional to its current load. Simulation confirms that our method helps reducing the oscillation of the web server load significantly.
The Effect of Oxygen Vacancy Concentration on Indium Gallium Oxide Solar Blind Photodetector
(2018-05-01)
Chen, Kuan-Yu
;
Hsu, Ching-Chien
;
Yu, Hsin-Chieh
;
Peng, Yu-Ming
;
Yang, Chih-Chiang
In this paper, amorphous indium-gallium-oxide solar-blind metal-semiconductor-metal photodetectors were fabricated by using co-sputtering method. Three samples with different oxygen concentrations, namely, sample A without oxygen, sample B with 2% oxygen concentration, and sample C with 4% oxygen concentration, were investigated. The applied bias was 5 V during device characterization. The ultraviolet (UV)-to-visible rejection ratios were 39, 9.9 x 10(3), and 1.1 x 10(5) for samples A, B, and C, respectively. The dynamic responses of the decay times were 5.79/52.12 s, 1.96/30.49 s, and 0.02/0.75 s for samples A, B, and C, respectively. In summary, the 4% oxygen concentration sample exhibited excellent UV-to-visible rejection ratio and superior decay time.