Browsing by Author "Liu, Jui-Min"

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Crystal Quality of 3C-SiC Influenced by the Diffusion Step in the Modified Four-Step Method
(2010)
Chen, Wei-Yu
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Wang, Wei-Lin
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Liu, Jui-Min
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Chen, Chien-Cheng
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Hwang, Jenn-Chang
The atomic arrangement and bonding characteristics of void-free 3C-SiC/Si(100) grown by the modified four-step method are presented. Without the diffusion step, Si-C bonds are partially formed in the as-carburized layer on Si(100). The ratio of C-C bonds to Si-C bonds is about 7:3, which can be lowered to about 1:9 after the diffusion step at 1350 degrees C for 5 min or at 1300 degrees C for 7 min according to C 1s core level spectra. The residual C-C bonds cannot be removed, which is associated with an irregular atomic arrangement (amorphous) located either at the 3C-SiC/Si(100) interface or at the intersection of twin boundaries in the 3C-SiC buffer layer based on the lattice image taken by transmission electron microscope. The diffusion step helps the formation of Si-C bonds more completely and results in a SiC buffer layer of high quality formed on Si(100) before the growth step. However, twins and stacking faults still appear in the 3C-SiC buffer layer after the diffusion step. The formation mechanism of the 3C-SiC buffer layer is proposed and discussed.
Efficiency Enhancement and Sensitive Broadband 1Hz similar to 1kHz of Power Generator by Recycling Vibration Energy on Automobile
(2012)
Wei, Mao-Qugn
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Ko, Fu-Hsiang
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Sun, Tai-Ping
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Chen, Hsuen-Li
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Lin, Yung-Bin
Based on novel design of moveable magnet between two mutually inimical magnetic forces without strict fabrication, for the first time, we demonstrate successfully a producible power generator with significant efficiency enhancement at broadband frequency range of 1 Hz similar to 1 kHz, 3D-colis stack-ability for output voltage improvement, and recycling vibration energy on automobile simultaneously. Even though the vibration frequency is as low as 1 Hz, two orders-of-magnitude improvements in normalized power (the ratio of power to product of external force and coil turns) provided from previous reports can be obtained. Further, comparing our device with maturely accelerometer chip (MMA7361) indicates that proposed strategies benefit harvesting vibration energy on driving automobile indeed. This vibrated power generator in-turn provides high potential for applications, such as human motion (1 Hz similar to 2 Hz), sporting (5 Hz similar to 10 Hz), and automotive (10 Hz similar to 1 kHz) etc..
Growth of 3C-SiC on Si(111) using the four-step non-cooling process
(2010-08-02)
Liu, Jui-Min
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Chen, Wei-Yu
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Hwang, J.
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Huang, C-F.
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Wang, Wei-Lin
A modified four-step method was applied to grow a 3C-SiC thin film of high quality on the off-axis 1.5 degrees Si(111) substrate in a mixed gas of C(3)H(8), SiH(4) and H(2) using low pressure chemical vapor deposition. The modified four-step method adds a diffusion step after the carburization step and removes the cooling from the traditional threestep method (clean, carburization, and growth). The X-ray intensity of the 3C-SiC(111) peak is enhanced from 5 x 10(4) counts/s (the modified three steps) to 1.1 x 10(5) counts/s (the modified four steps). The better crystal quality of 3C-SiC is confirmed by the X-ray rocking curves of 3C-SiC(111). 3C-SiC is epitaxially grown on Si( 111) supported by the selected area electron diffraction patterns taken at the 3C-SiC/Si(111) interface. Some (111) stacking faults and twins appear inside the 3C-SiC, which may result from the stress induced in the 3C-SiC thin film due to lattice mismatch. The diffusion step plays roles in enhancing the formation of Si-C bonds and in reducing the void density at the 3C-SiC/Si(111) interface. (C) 2010 Elsevier B.V. All rights reserved.
The photovoltaic-thermal system parameter optimization design and practical verification
(2019-01-15)
Kuo, Chung-Feng Jeffrey
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Liu, Jui-Min
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Umar, Mega Lazuardi
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Lan, Wei-Lun
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Huang, Chao-Yang
This study used the Taguchi method combined with Analytic Hierarchy Process (AHP) to present optimization design of the Photovoltaic-Thermal (PV/T) system for improving the two quality characteristics namely electrical and thermal efficiency. The control parameters for PV/T design including the collector plate material, collector azimuth, number of collector tubes, mass flow rate, collector angle, and storage tank volume to area (V/A) ratio are crucial factors affecting the performance of the PV/T. First, Taguchi method coupled with main effect analysis (MEA) and analysis of variance (ANOVA) was used to obtain the best parameters combination on each single quality characteristic of electricity and thermal efficiency. In order to achieve the maximum total efficiency of the PV/T system, multi-quality analysis AHP was used to obtain the optimal control parameters combination according to the contribution degrees of quality weight. Then, the computational fluid dynamic (CFD) software used to simulate the PV/T module thermal distribution before and after optimization. The optimization control parameters combination are: collector plate material is copper, collector azimuth is due south, number of collector tubes is 12, mass flow rate is 0.01 kg/s-m(2), collector angle is 25 degrees, and V/A ratio is 123. The effectiveness of the proposed method was evaluated by the confirmation experiments. The optimization properties under these parameters are electrical efficiency 14.29% and thermal efficiency 44.96% which is improved than traditional PV/T system (electrical efficiency 12.74% and thermal efficiency 34.06%). The findings of CFD showed that the temperature of the PV/T module decreased by about 10 degrees C after optimality analysis, and the coefficient of correlation between the simulated and actual PV/T water temperatures was 0.991 (very close to 1). The CFD simulated performance testing proposed in this study has a good verification effect.