銀奈米顆粒吸附氧化鋅奈米片生長在玻璃基板上之氣體感測器與場發射元件光電特性分析

Gas sensor and Field emission Characteristics of Ag nanoparticle-adsorption Zinc Oxide nanosheets grown on glass substrates

簡仁則(Jen-Tse Chien)

指導教授 ： 楊勝州

國立虎尾科技大學/電機資訊學院/電子工程系碩士班/碩士(2016年)

摘要

氧化鋅作為n型半導體材料有著許多特性，例如寬的直接能隙(3.37 eV)，較高的激子結合能，在室溫下有熱穩定性，而且成本低。而已知的貴金屬奈米顆粒，例如銀、金和白金，用於氧化鋅奈米結構，將可以提供電子給氧化鋅奈米結構，而金屬奈米粒子和尖端放電不僅可以增加場發射特性，而且減少Turn-on電場。在這項研究中，主要是將銀奈米顆粒吸附氧化鋅奈米片通過水溶液法和光化學合成法成功的生長在玻璃基板上。將未吸附金屬粒子之氧化鋅和銀奈米粒子吸附氧化鋅奈米片進行結構和光電特性的研究。所製備的樣品的特性通過場發射掃描式電子顯微鏡(SEM)、X射線繞射儀(XRD)、能量散佈分析儀(EDS)、穿透式顯微鏡(TEM)來證實銀奈米顆粒吸附在氧化鋅奈米片。本實驗使用水溶液法成功合成氧化鋅奈米片，通過光化學合成法成功的在奈米片上合成銀奈米顆粒並吸附在表面上，其目的在於提升氣體感測之靈敏度，其中銀奈米顆粒吸附於氧化鋅奈米片感測器的工作溫度為200℃下有最佳的感測能力，當氧化鋅奈米片在1100 ppm的二氧化碳其響應值為12%，而銀奈米顆粒吸附氧化鋅奈米片在1100 ppm的二氧化碳其響應值可提升至79%，由此可知銀奈米顆粒當作奈米片的金屬觸媒有效的提升氣體感測器的靈敏特性。對純的氧化鋅和銀奈米粒子吸附氧化鋅奈米片進行場發射量測。在未照光中場發射曲線表示純的氧化鋅和銀奈米顆粒吸附氧化鋅奈米片的開啟電場的值分別為5.3和3.2 V/μm和它的增強因子分別為3002和3420。在紫外光照射下純的氧化鋅和銀奈米顆粒吸附氧化鋅奈米片的開啟電場的值分別為4.3和2V/μm和增強因子分別為3276和4815。而結果表明銀奈顆粒吸附氧化鋅奈米片比純的氧化鋅有較低的開啟電場和較高的增強因子。因此，銀奈米顆粒吸附氧化鋅奈米片會提升材料的導電性。

關鍵字

氧化鋅奈米片 ； 銀奈米顆粒 ； 場發射元件 ； 氣體感測器

並列摘要

The Zinc Oxide (ZnO) have some advantages, including a wide direct bandgap of 3.37 eV, a high exciton binding energy with thermal stability at room temperature, and low cost. It is known that noble metal nanoparticles adsorption ZnO nanostructure can be increased field emission characteristics due to it can be provided electron for ZnO nanostructure. In this study, Ag nanoparticle adsorption ZnO nanosheets were successfully grown on glass substrates by the aqueous solution method and photochemical synthesis method. The as-prepared samples were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), transmission electron miscroscope (TEM) confirmed that Ag nanoparticle grown on the ZnO nanosheets. The CO2 sensing characteristics of pure ZnO and Ag nanoparticle-adsorption ZnO were compared using a gas sensing measurement system. The sensitivity, operating temperature, and response were systematically investigated based on the change in electrical resistance of the materials in the presence of CO2. It was found that the pure ZnO showed a maximum response to 1100 ppm CO2 (12%) at an operating temperature of 200℃. Experimental results confirmed that Ag nanoparticle- adsorption ZnO showed a maximum response to 1100 ppm CO2 (79%) at an operating temperature of 200℃. The results indicate that the Ag nanoparticle adsorption ZnO nanosheets exhibit enhanced gas sensing characteristics. The field emission characteristics of pure ZnO and Ag nanoparticle adsorption ZnO nanosheets are studied. It was found that the measured turn-on electric fields of the pure ZnO and Ag nanoparticle adsorption ZnO nanosheets were 5.3 and 3.2 V/μm, and the field enhancement factor were 3002 and 3420, respectively, in the dark. The measured turn-on electric fields of the pure ZnO and Ag nanoparticle adsorption ZnO nanosheets were 4.3 and 2 V/μm, and the field enhancement factor were 3276 and 4815 under UV illumination, respectively. The field emission performance of the Ag nanoparticle adsorption ZnO nanosheets were lower turn-on electric fields and larger β values than pure ZnO. The results indicate that the Ag nanoparticle adsorption ZnO nanosheets exhibit enhanced field emission characteristics.

並列關鍵字

ZnO nanosheets ； Ag nanoparticle ； Field Emission ； Gas sensor

參考文獻

[39]施丞達, “化學氣象沈積法製備氮化鎵奈米線及奇特行性研究”, 國立成功大學材料科學及工程學系, 2004。

[1]U.S. National Oceanic and Atmospheric Administration.

[2]J. Chen and T. Fujita., “Effects of Annealing on Photoluminescence of ZnO Thin Film Prepared by Vapor Phase Growth”, J. Appl. Phys., 2003.

[3]Y. Liu, C.R. Gorla, S. Liang, N. Emanetoglu, Y. Lu, H. Shen, M. Wraback, “Ultraviolet detectors based on epitaxial ZnO films grown by MOCVD”, J. Electron. Mater, pp. 69-74, 2000.

[4]V.R. Shinde, T.P. Gujar, C.D. Lokhande, “LPG sensing properties of ZnO films prepared by spray pyrolysis method: Effect of molarity of precursor solution”, Sens. Actuators B., pp. 551-559, 2007.