Browsing by Author "Wu, Yewchung Sermon"

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Effects of laser sources on the reverse-bias leakages of laser lift-off GaN-based light-emitting diodes
(2007-06-18)
Wu, Yewchung Sermon
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Cheng, Ji-Hao
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Peng, Wei Chih
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Ouyang, Hao
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材料科學與工程學系
The KrF pulsed excimer laser (248nm) and the frequency-tripled neodymium doped yttrium aluminum garnet laser (355nm) have been used to separate GaN thin films from sapphire substrates and transfer to bond other substrate. However, these processes would increase the dislocation density, resulting in an increase of the leakage current. In this study, the effects of these two laser sources on the reverse-bias leakages of InGaN-GaN light-emitting diodes were studied. (c) 2007 American Institute of Physics.
Effects of oxygen in Ni films on Ni-induced lateral crystallization of amorphous silicon films at various temperatures
(2006-09-01)
Lin, You-Da
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Wu, Yewchung Sermon
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材料科學與工程學系
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Department of Materials Science and Engineering
Effects of oxygen in Ni films on. the Ni-induced lateral crystallization (NILC) of amorphous silicon (a-Si) films at various temperatures have been investigated. It was found that oxygen in Ni films retarded the nucleation of polycrystalline silicon (poly-Si) from a-Si, but had little effect on the growth rate of poly-Si. This is because that needed an incubation period to be reduced to Ni metal for the subsequent mediated crystallization of a-Si.
Improved Electrical Performance and Reliability of Poly-Si TFTs Fabricated by Drive-In Nickel-Induced Crystallization with Chemical Oxide Layer
(2011-06-01)
Lai, Ming-Hui
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Wu, Yewchung Sermon
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Chang, Chih-Pang
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材料科學與工程學系
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Department of Materials Science and Engineering
Ni-metal-induced crystallization (MIC) of amorphous Si (alpha-Si) has been employed to fabricate low-temperature polycrystalline silicon thin-film transistors (TFTs). However, the Ni residues degrade the device performance. In this study, a new method for manufacturing MIC-TFTs using drive-in Ni-induced crystallization with a chemical oxide layer (DICC) is proposed. Compared with that of MIC-TFTs, the on/off current ratio (I (on)/I (off)) of DICC-TFTs was increased by a factor of 9.7 from 9.21 x 10(4) to 8.94 x 10(5). The leakage current (I (off)) of DICC-TFTs was 4.06 pA/mu m, which was much lower than that of the MIC-TFTs (19.20 pA/mu m). DICC-TFTs also possess high immunity against hot-carrier stress and thereby exhibit good reliability.
Improved Gettering Efficiency of Ni from Nickel-Mediated Crystallization Silicon Using Phosphorus-Doped Amorphous Silicon
(2009-06-01)
Wang, Bau-Ming
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Wu, Yewchung Sermon
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材料科學與工程學系
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Department of Materials Science and Engineering
Ni-metal-induced lateral crystallization (NILC) has been utilized to fabricate polycrystalline silicon thin-film transistors. However, the NILC process often leads to Ni and NiSi(2) precipitates being trapped. In this study, two kinds of films were used as gettering layers: (1) amorphous Si and (2) phosphorus-doped amorphous Si. After annealing at 550A degrees C for 12 h, it was found that phosphorous dopant did improve the gettering efficiency of amorphous Si.
Improved uniformity and electrical performance of continuous-wave laser-crystallized TFTs using metal-induced laterally crystallized si film
(2008-11-01)
Chang, Chih-Pang
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Wu, Yewchung Sermon
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材料科學與工程學系
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Department of Materials Science and Engineering
Continuous-wave (CW) laser crystallization (CLC) of amorphous Si (alpha-Si) has previously been employed to fabricate high-performance low-temperature polycrystalline silicon (poly-Si) thin-film transistors (TFTs). Unfortunately, their uniformity was poor because the shape of the beam profiles was Gaussian. In this study, alpha-Si film was replaced by Ni-metal-induced laterally crystallized Si (MILC-Si). MILCLC-Si was MILC-Si irradiated by a CW laser (lambda approximate to 532 nm and power approximate to 3.8 W). It was found that the performance and uniformity of the metal-induced laterally crystallized continuous-wave laser crystallization - thin film transistors (MILCLC-TFTs) were much better than those of the CLC-TFTs. Therefore, the MILCLC-TFT is suitable for application in systems on panels.
Investigations of Electro-hydrothermally Grown ZnO Nanostructures on Copper Grids
(2017-01-01)
Yu, Tzu-Yi
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Hung, Chen Hao
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Lee, Yu Shan
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Lin, Chia Feng
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Su, Wei Min
Two types of ZnO nanostructures were electro-hydrothermally deposited on mesh 100 and 200 copper grids. To investigate the nanostructures, multiple material analyses were used to analyze the material properties. FESEM images indicate that nanoflowers/nanorods could be grown on the mesh 100 copper grids while a single layer of ZnO nanorods could be grown on the mesh 200 copper grids. Since the size of the grid holes might influence the chemical reactions during the growth of the nanostructures, all the other material analyzes also reveale1 distinct material characteristics of these two types of nanostructures on the copper grid. Based on the experimental results, modulating the ZnO nanostructure will be helpful for future applications of ZnO nanostructures on copper substrates.
Microstructural Characterization of Multilayer Metal Stack on InGaAs/InP Contact
(2020-08-01)
Hsu, Chih-Lin
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Wu, Yewchung Sermon
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Chen, Szu-Hung
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Lin, Kun-Lin
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材料科學與工程學系
Al/InGaAs, Al/Ti/InGaAs, and Al/Ni/InGaAs contacts were prepared by conducting rapid thermal annealing at different temperatures, and the interfacial reaction was characterized using x-ray diffraction, atomic force microscopy, and transmission electron microscopy. The specific contact resistivity of the metal film contacts onn-InGaAs was determined using a circular transmission line measurement. The Al/Ni/InGaAs, Al/Ti/InGaAs, and Al/InGaAs stack contacts remained stable even after the samples were subjected to annealing at 400 degrees C. When the annealing temperature increased to 600 degrees C, Al began melting and clustering due to the formation of Al(Ga) to form Al/InGaAs. An AlNi phase was formed at the interfaces of an Al/Ni/InGaAs contact when it was annealed above 400 degrees C, thus causing the specific resistance and roughness to increase dramatically. Each element of the Al/Ti/InGaAs contact began diffusing when it was annealed beyond 400 degrees C, and an Al3Ti phase was formed above 500 degrees C. The formation of Al3Ti led to the increase in the specific resistance and roughness. Moreover, the as-deposited Al/Ni/InGaAs, Al/Ti/InGaAs and Al/InGaAs samples had specific resistances of 1.11 x 10(-5) omega cm(2), 5.11 x 10(-5) omega cm(2), and 1.14 x 10(-4) omega cm(2), respectively. These results reveal that to develop the Al/Ti/InGaAs and Al/Ni/InGaAs stacks on InGaAs with a low parasitic resistance, the processing temperature should be lower than 400 degrees C.