摘要
本研究主要探討氧化石墨烯(Graphene oxides, GOs）與氧化石墨烯摻雜銀奈米粒子複合材料（Composites of graphene oxides and Silver nanoparticles, GOs-AgNPs）在雷射剝蝕還原（Laser ablation and reduction, LAR）作用後形成還原石墨烯（rGOs）與還原石墨烯-金屬奈米粒子複合物（rGOs-AgNPs）之場發效應特性，接著引入聚乙烯醇-硝酸銀(Composites of Polyvinyl alcohol and Silver nitrate,PVA-AgNO3 )當作導電層材料，並且探討相關機制與特性。
第一部分實驗為GO還原成rGO後具有導電薄膜並同時當作場發源，接著摻雜銀奈米粒子作修飾的研究，GO在雷射功率31.73 W作用還原成rGO後，片電阻~2.2 kΩ/□，此時有一相對低的啟動電場 (Turn-on field, Eturn-on @ J=10 μA/cm2) ~4.21 V/μm，對應的場發射增強因子 (field enhancement factor, β) ~1831。接著引入銀奈米粒子做修飾，當銀奈米粒子之氧化石墨烯薄膜（GO-AgNPs）在摻雜濃度為4.25×10-4 M的情況下，經雷射拔氧還原後，片電阻~1.5 KΩ/□，場發射特性Eturn-on降低至4.17 V/μm，對應的β~2989，確定經由添加銀奈米粒子後降低了啟動電壓，以及提高了場發射增強因子。
第二部分則是增加了PVA-AgNO3當作導電層的使用，並將GO轉印於PVA-AgNO3上，接著雷射功率31.73 W作用還原成rGO，而其中PVA-AgNO3加熱還原成PVA/AgNPs後，導電層片電阻為~0.1 Ω/□。；而場發射特性 Eturn-on 從4.21 V/μm下降至1.88 V/μm，β由1831上升至6363。；最後實驗將銀奈米粒子以及導電層同時應用，GO-AgNPs轉印於PVA-AgNO3上，銀奈米粒子摻雜濃度為4.25 x10-4 M 的情況下，雷射功率31.73 W作用還原成rGO/AgNPs，場發射特性Eturn-on 由4.17 V/μm下降至1.6 V/μm，β由2989上升至7962，經過增加導電層以及摻雜銀奈米粒子這兩種方式修飾獲得的實驗參數為本實驗的最佳值。
關鍵字：
氧化石墨烯、雷射、銀奈米粒子、場發射效應、聚乙烯醇-硝酸銀

Field emission properties of a reduced graphene oxide (rGO) thin film were characterized in this study. The rGO thin film was prepared based on the following steps. Initially, commercially available graphene oxide (GO) sheets were uniformly dispersed in a solvent. The solution was then deposited upon a glass substrate to form a GO thin film. A pulsed laser was employed to irradiate on the GO thin film. Due to its absorption of the incident laser energy, the GO thin film was instantly increased to an elevated temperature and thermally reduced into an rGO thin film. The field-emission properties are mainly dependent upon the surface morphology and conductivity of the resultant rGO thin film. By varying both the laser power and the laser exposing patterns, the field-emission characteristics of the rGO thin film could be regulated. Results show a laser-annealed rGO thin film with the turn-on field, Eturn-on, of 4.21 V/μm and field enhancement factor, β, of 1831 can be obtained using laser power of 31.73 W. In addition to the rGO thin film, the field-emission properties of a thin film of rGO sheets blending with Ag nanoparticles, rGO-AgNPs thin film, were also examined in this study,the rGO-AgNPs thin film with the turn-on field, Eturn-on, of 4.17 V/μm and field enhancement factor, β, of 2989 can be obtained using laser power of 31.73 W.
Here a thin film initially, containing GO sheets, polyvinyl alcohol (PVA) and silver nitrate (AgNO3) had to be prepared prior to the subsequent laser irradiation. It was accomplished by mixing the solution of GO sheets with both the PVA and AgNO3 solutions. The existence of the Ag nanoparticles enhanced the conductivity of the resultant rGO thin film of the field emission properties: the turn-on field was reduced to 1.88 V/μm and the field enhancement factor was increased to 6363. rGO-AgNPs thin film with the turn-on field, Eturn-on, of 1.6 V/μm and field enhancement factor, β, of 7962 can be obtained using laser power of 31.73 W.

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