Browsing by Author "Chen, Wei-Chun"

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    Effects of doping concentration and annealing temperature on properties of highly-oriented Al-doped ZnO films
    (Elsevier, 2006-01-18) Kuo, Shou-Yi; Chen, Wei-Chun; Lai, Fang-I; Cheng, Chin-Pao; Kuo, Hao-Chung; Wang, Shing-Chung; Hsieh, Wen-Feng
    Transparent and conductive high-preferential c-axis-oriented Al-doped zinc oxide (ZnO:Al, AZO) thin films have been prepared by the sol–gel route. Film deposition was performed by spin-coating technique on Si(1 0 0) and glass substrate. Structural, electrical and optical properties were performed by XRD, SEM, four-point probe, photoluminescence (PL) and UV-VIS spectrum measurements. The effects of annealing temperature and dopant concentration on the structural and optical properties are well discussed. It was found that both annealing temperature and doping concentration alter the microstructures of AZO films. Also, PL spectra show two main peaks centered at about 380 nm (UV) and 520 nm (green). The variation of UV-to-green band emission was greatly influenced by annealing temperatures and doping concentration. Reduction in intensity ratio of UV-to-green might possibly originate from the formation of Al–O bonds and localized Al-impurity states. The minimum sheet resistance of 104 Ω/□ was obtained for the film doped with 1.6 mol% Al, annealed at 750 °C. Meanwhile, all AZO films deposited on glass are very transparent, between 80% and 95% transmittance, within the visible wavelength region. These results imply that the doping concentration did not have significant influence on transparent properties, but improve the electrical conductivity and diversify emission features.
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    Investigation of Annealing-treatment on the Optical and Electrical Properties of Sol-Gel-Derived Zinc Oxide Thin Films
    (2005-05-31) Chen, Wei-Chun; Cheng, Chin-Pao; Kuo, Shou-Yi
    Highly preferential c-axis orientation ZnO thin films on Si(100) and quartz substrates have been achieved by sol-gel method. Structural investigation including surface morphology and microstructure was carried out by XRD, SEM and AFM measurements. Also, optical properties were determined by photoluminescence, ellipsometry and UV-VIS spectrum analyses. XRD results indicated that an extremely sharp (002) peak will dominate under optimum annealing-treatment condition. Moreover, thin film quality and the morphology were improved by annealing treatment. The SEM images show that the grains sizes increased with increasing annealing temperature up to 750 oC, where the particle size was about 50 nm. Photoluminescence spectra revealed two main peaks centered at about 380 nm and 520 nm, corresponding to the band-edge and defect-related emission. The variation in UV emission intensity was attributed to the competition between the excitonic and nonradiative recombination. It was proposed that annealing temperature plays a key role in the formation of defects, which is strongly related to the nonradiative recombination centers. In addition, optical transmittance spectra demonstrated that these films are very transparent (~90%) in the range of 380-800 nm wavelength, and optical band-gap was determined accordingly. The impact of the thermal treatment on the structural and optical properties was discussed in detail.
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    Investigation of annealing-treatment on the optical and electrical properties of sol–gel-derived zinc oxide thin films
    (Elsevier, 2005-08-01) Kuo, Shou-Yi; Chen, Wei-Chun; Cheng, Chin-Pao
    Highly preferential c-axis orientation ZnO thin films on Si(100) and quartz substrates have been achieved by the sol–gel method. Structural investigation including surface morphology and microstructure was carried out by XRD, SEM and AFM measurements. Also, optical properties were determined by photoluminescence, ellipsometry and UV–VIS spectrum analyses. XRD results indicated that an extremely sharp (002) peak will dominate under optimum annealing-treatment condition. Moreover, thin film quality and the morphology were improved by annealing treatment. The SEM images show that the grain sizes increased with increasing annealing temperature up to 750 ring operatorC, where the particle size was about 50 nm. Photoluminescence spectra revealed two main peaks centered at about 380 nm and 520 nm, corresponding to the band-edge and defect-related emission. The variation in UV emission intensity was attributed to the competition between the excitonic and nonradiative recombination. It was proposed that annealing temperature plays a key role in the formation of defects, which is strongly related to the nonradiative recombination centers. In addition, optical transmittance spectra demonstrated that these films are very transparent (not, vert, similar90%) in the range of 380–800 nm wavelength, and optical band-gap was determined accordingly. The impact of the thermal treatment on the structural and optical properties was discussed in detail.
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    Observation of ultraviolet lasing from polycrystalline zno films
    (2005-07-11) Kuo, Shou-Yi; Chen, Wei-Chun; Lai, Fang–I; Cheng, Chin-Pao; Kuo, Hao-Chung; Wang, Shing-Chung
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    Ultraviolet Lasing of Sol–Gel-Derived Zinc Oxide Polycrystalline Films
    (Japan Society of Applied Physics, 2006-04-25) Kuo, Shou-Yi; Chen, Wei-Chun; Lai, Fang-I; Cheng, Chin-Pao; Kuo, Hao-Chung; Wang, Shing-Chung
    The effect of post-annealing on sol–gel-derived ZnO films has been investigated. For these films, structural investigations including analyses of surface morphology and microstructures were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, optical properties were determined by photoluminescence analysis, ellipsometry and optical pumping measurement. The XRD results indicate that the (002) peak will predominate with increasing annealing temperature. SEM images show that grain size increased with annealing temperature. Moreover, photoluminescence spectra revealed the enhancement in UV emission intensity with annealing temperature, which was attributed to an improvement in crystal quality. Room-temperature ultraviolet random lasing action was observed in the ZnO films. The threshold intensity for the lasing was estimated to be ∼70 kW/cm2. Furthermore, it was found that the formation of random laser action is affected by post-annealing, which is associated to the presence of a high-gain medium and efficient light scattering.
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    以奈米探針親和質譜法分析單一醣蛋白質體學於肝疾病中之差異
    (2015) 陳威君; Chen, Wei-Chun
    現今診斷肝癌最常見的方法，如超音波掃描影像檢查或血清檢驗甲型胎兒蛋白(alpha-fetoprotein, AFP)濃度，都仍無法正確分辨癌症腫瘤特性或對甲型胎兒蛋白偵測的靈敏度及特異度不足。為了找尋出高靈敏度以及特異性的理想腫瘤標記分子，許多研究開始朝向分析肝疾病中標記蛋白的醣基化修飾與其變化。由許多文獻指出，血紅素結合蛋白(Haptoglobin, Hp)上的醣基化修飾的變化跟發展成肝癌的過程中有很大的關係，因此在本篇論文中，我們發展出兩種不同的親合性奈米探針結合質譜分析技術，對於單一生物標記血紅素結合蛋白上醣基化修飾在肝疾病中的改變研究，以找出早期診斷肝癌的腫瘤標記分子。 第一個策略是用磁性奈米粒子修飾上跟目標蛋白血紅素結合蛋白有親和性的血紅蛋白(Hemoglobin, Hb)，純化出血液中的血紅素結合蛋白，再利用親水性作用層析法(Hydrophilic interaction chromatography，HILIC)萃取其醣胜肽，並結合質譜分析以鑑定特定位點之醣型。此研究分析了33例肝疾病病患，包括11例肝癌、11例肝硬化以及11例B型肝炎病人。我們成功地在肝癌、肝硬化以及B型肝炎病人分別鑑定到183、169、164條醣胜肽，醣基化的位置是位於天冬醯胺(Asparagine, Asn) Asn184, Asn207, Asn211以及Asn241。由比對醣胜肽的結果得知，約有2種雙角分支之唾液酸醣結構可在每一肝疾病族群中大於10個病人以上鑑定而得。此外，我們鑑定到28個獨特的醣胜肽在肝癌中出現，其中包括了5個雙角分支及三角分支的核心岩藻醣型，推測這些特定位點的獨特醣型可能有助於區分肝癌、肝硬化與B型肝炎病人。因此，這些常見或獨特的岩藻醣基化或是帶有不同分支的醣結構在不同醣基化位置的變化，將可提供肝癌在早期診斷的新方向。 在第二部分，我們發展出一鍋化(One Pot)策略對於蛋白質以及醣胜肽純化以及生物標記分子醣基化修飾的鑑定。同時利用兩種奈米探針：修飾上血紅蛋白的二氧化矽奈米粒子(Hb@SiO2)純化目標蛋白; 修飾上配位體的磁性奈米粒子(ligand@MNP)純化出醣胜肽。經過條件最佳化以及方法評估後，此一鍋化方法可以減少兩倍以上的醣胜肽含量和醣胜肽鑑定數目的流失。我們將此策略也應用在肝病病患的分析上(三例肝癌，三例肝硬化及三例B型肝炎病人)，亦有效鑑定到雙角分支之岩藻醣基化結構只會在肝癌中出現，且不存在於肝硬化病人以及B型肝炎病人中。此一鍋化方法不僅可以增加醣胜肽的鑑定，對於特定醣結構(岩藻醣基化以及唾液酸苷化)的研究也有更好的偵測靈敏度。
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    使用射頻電漿輔助化學束磊晶成長氮化銦磊晶材料於表面氮化處理矽(111)基板之研究
    (2019) 陳聖; CHEN, SHENG
    本研究利用射頻電漿輔助化學束磊晶系統於矽(111)基板上製備氮化矽緩衝層，針對製備緩衝層之電漿氮氣流量比、氮化時間進行研究，探討氮化銦於不同條件之緩衝層生長其結構、結晶性及電子遷移率變化。研究結果顯示，在實驗條件下矽(111)基板表面會產生氮化矽層(SixNy layer)，隨著氮化時間或流量增加，表面會形成β-Si3N4，有助於纎鋅礦結構氮化銦磊晶生長。透過X光繞射分析證實經過表面氮化處理的試片皆能成長氮化銦磊晶。本研究再進行製備氮化氮化銦/氮化矽雙緩衝層於矽(111)基板，並針對氮化銦磊晶薄膜之特性進行探討，研究結果證實，使用雙緩衝層技術之氮化銦磊晶薄膜能提高結晶性及電性，隨著製備氮化矽層時氮氣流量及氮化時間增加，結晶性及電性均有所提升。