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日 期： 2010.08.09 指導老師：林克默 學 生：陳冠廷. Outline. Introduction Experimental 3. Results and discussion 4. Conclusions. 1.Introduction.
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日 期：2010.08.09 指導老師：林克默 學 生：陳冠廷
Outline • Introduction • Experimental 3. Results and discussion 4. Conclusions
1.Introduction • Nanocomposite ZnO–Ag thin film containingnano-sized Ag particles have been grown on glass substrateby spin-coating technique using zinc acetate dihydrate asstarting precursor in 2-propanol as solvent and monoethanolamineas stabilizer. Silver nanoparticles were added inthe ZnO sol using silver nitrate dissolved in ethanol-acetonitrile.Their structural, electrical, crystalline size andoptical 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, andmonoethanolamine,0.86 mL (99%) (MEA) (Sigma–Aldrich) as acomplexing agent while stirring at 60 C for 1 h to achievea transparent ZnO sol and aged for 1 day. • Silver sol wasprepared using silver nitrate, AgNO3, 0.777 g, (99.9%)(Aldrich) as precursor, dissolved in the mixture of ethylalcohol, 5 mL (98%) (Merck) as a solvent and acetonitrile,5 mL (99.9%) (Aldrich) as a complexing agent whilestirring at 25 ℃ for 1 h. ZnO sol was added to the silversol under gentle stirring to attain a sol mixture with[Ag] = 0.175 M and [ZnO] = 0.541 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] = 0.148 M, [Ag] = 0.110 M and [Ag] = 0.068 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 usingsol–gel spin coating technique with 3,600 rpm for 45 s.The glass substrate was cleaned with acetone, rinsed withdeionized water and subsequently dried using a flowing drynitrogen gas before deposition.
3 .Results and discussion • Fig. 1 TG-DTA curves of a pure ZnO and b nanocomposite ZnO–Ag, [Ag] = 0.148 M gels, which had been dried in 100 ℃
Fig. 2 XRD pattern of ZnO–Ag thin films, [Ag] = 0.148 Mpreheated 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] = 0.148 Mat 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 molarratio a [Ag] = 0.175 b [Ag] =0.148 M c [Ag] = 0.110 Md [Ag] = 0.068 M ande pure ZnO thin films, preheated at 275 ℃and annealed at 550 ℃ Fig. 5 XRD pattern of ZnO–Ag, [Ag] = 0.148 M thin films withdifferent layers number a 8, b 6, c 5, d 4, e 2 layers,preheatedat 275 ℃ for 10 min and annealed for 2 h at 550 ℃
Fig. 6FT-IR spectrum of apure ZnO bnanocomposite ZnO–Ag,[Ag] = 0.148 M annealed at 550 ℃
Fig. 7 Cross-section SEM image for one layer of nanocompositeZnO–Ag film with 379 nm thickness (top), a SEM image of pure ZnOthin film b nanocomposite ZnO–Ag, [Ag] =0.148 M thin filmpreheated in 275 ℃ andannealed at 550 ℃, with 30,000magnifications
Fig. 8 AFM images of surface morphology the thin films a pure ZnOb nanocomposite ZnO–Ag, [Ag] = 0.148 M preheated at 275 ℃ and annealed at 550 ℃
Fig. 9 Optical absorption spectra of a nanocomposite ZnO–Ag, [Ag] = 0.110 M thin film bnanocomposite ZnO–Ag, [Ag] =0.068 M c pure ZnO thin filmpreheated at 275 ℃ and annealed at550 ℃ Fig. 10 Optical absorption spectra of nanocomposite ZnO–Ag,[Ag] = 0.148 M thin film preheated at 275 ℃ and annealedata 350 ℃ b 450 ℃ and c 550 ℃
Fig. 11 Transmission electron microscopic (TEM) images of nanocompositeZnO–Ag, [Ag] = 0.148 M dried sol at 100 ℃ andpreheated at 275 ℃ with a 80,000 and b 100,000 magnifications
4. Conclusion • In summary we have successfully synthesized nanocompositeZnO–Ag thin films through a simple sol–gel methodat 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.
