日 期： 指導老師：林克默 學 生：陳冠廷

Outline 1.Introduction 2.Experimental 3. Results and discussion 4. Conclusions

1.Introduction Nanocomposite ZnO–Ag thin film containing nano-sized Ag particles have been grown on glass substrate by spin-coating technique using zinc acetate dihydrate as starting precursor in 2-propanol as solvent and monoethanolamine as stabilizer. Silver nanoparticles were added in the ZnO sol using silver nitrate dissolved in ethanol-acetonitrile. Their structural, electrical, crystalline size and optical properties were investigated as a function of preheating, annealing temperature and silver content.

2. Experimental details ZnO sol was prepared using zinc acetate dihydrate,Zn(C2H3O2)22H2O, 3.1 g, (99.9%) (Sigma– Aldrich) (ZA) as precursor, dissolved in the mixture of isopropyl alcohol,15 mL (99%) (Merck) (IPA) as a solvent, and monoethanolamine,0.86 mL (99%) (MEA) (Sigma–Aldrich) as a complexing agent while stirring at 60 C for 1 h to achieve a transparent ZnO sol and aged for 1 day. Silver sol was prepared using silver nitrate, AgNO3, g, (99.9%) (Aldrich) as precursor, dissolved in the mixture of ethyl alcohol, 5 mL (98%) (Merck) as a solvent and acetonitrile, 5 mL (99.9%) (Aldrich) as a complexing agent while stirring at 25 ℃ for 1 h. ZnO sol was added to the silver sol under gentle stirring to attain a sol mixture with [Ag] = M and [ZnO] = M (molar ratio of Agto ZnO was 32%). The resultant sol was left to age for3 days at ambient temperature in a closed vessel. Similar sol mixtures with an appropriate ratio of ratio of Ag to ZnO sol were prepared to attain a sols of [Ag] = M, [Ag] = M and [Ag] = M. The molar ratio of Ag to Zn for these sol mixtures was 20, 12 and 5%respectively. In the present study the nanocomposite ZnO–Ag thin films were deposited on glass substrate using sol–gel spin coating technique with 3,600 rpm for 45 s.The glass substrate was cleaned with acetone, rinsed with deionized water and subsequently dried using a flowing dry nitrogen gas before deposition.

3.Results and discussion Fig. 1 TG-DTA curves of a pure ZnO and b nanocomposite ZnO–Ag, [Ag] = M gels, which had b een dried in 100 ℃

Fig. 2 XRD pattern of ZnO–Ag thin films, [Ag] = M preheated at different temperature a 300 ℃, b 275 ℃, c 250 ℃, d 225 ℃ and e 200 ℃ and annealed at 550 ℃ Fig. 3 XRD pattern of nanocomposite ZnO–Ag, [Ag] = M at different annealing temperature a 850 ℃, b 750 ℃, c 650 ℃ d 550 ℃, e 450 ℃ and f 350 ℃

Fig. 4 XRD pattern of ZnO–Ag thin films with different molar ratio a [Ag] = b [Ag] = M c [Ag] = M d [Ag] = M and e pure ZnO thin films, preheated at 275 ℃ and annealed at 550 ℃ Fig. 5 XRD pattern of ZnO–Ag, [Ag] = M thin films with different layers number a 8, b 6, c 5, d 4, e 2 layers, preheated at 275 ℃ for 10 min and annealed for 2 h at 550 ℃

Fig. 6 FT-IR spectrum of a pure ZnO b nanocomposite ZnO–Ag, [Ag] = M annealed at 550 ℃

Fig. 7 Cross-section SEM image for one layer of nanocomposite ZnO–Ag film with 379 nm thickness (top), a SEM image of pure ZnO thin film b nanocomposite ZnO–Ag, [Ag] = M thin film preheated in 275 ℃ and annealed at 550 ℃, with 30,000 magnifications

Fig. 8 AFM images of surface morphology the thin films a pure ZnO b nanocomposite ZnO–Ag, [Ag] = M preheated at 275 ℃ and annealed at 550 ℃

Fig. 9 Optical absorption spectra of a nanocomposite ZnO–Ag, [Ag] = M thin film b nanocomposite ZnO–Ag, [Ag] = M c pure ZnO thin film preheated at 275 ℃ and annealed at 550 ℃ Fig. 10 Optical absorption spectra of nanocomposite ZnO– Ag, [Ag] = M thin film preheated at 275 ℃ and annealed at a 350 ℃ b 450 ℃ and c 550 ℃

Fig. 11 Transmission electron microscopic (TEM) images of nanocomposite ZnO–Ag, [Ag] = M dried sol at 100 ℃ and preheated at 275 ℃ with a 80,000 and b 100,000 magnifications

4. Conclusion In summary we have successfully synthesized nanocomposite ZnO–Ag thin films through a simple sol–gel method at room temperature. The influence of silver content, preheatingand post-annealing temperature on the structuraland photonic properties of nanocomposite ZnO–Ag thinfilm is investigated. Crystalline phase and optical absorptionof nanocomposite ZnO–Ag thin films was improved atoptimal preheating and annealing temperature of 275 and550 ℃ respectively. The amount of Ag content was foundto control the absorption band.

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