Effect of Ag nanostructures and annealing process on the localized surface plasmon resonance properties of Ag-based AZO films

Abstract

Ag nanoparticles were obtained in Ag/AZO and AZO/Ag/AZO films by magnetron sputtering method at room temperature with different deposition time. The morphology of Ag nanoparticles is strongly affected by the particle size, shape and distribution as well as annealing temperatures, which determine the optical response of films. The high quality of AZO film with better crystallinity can enhance the optical transmittance and a good coverage by AZO as top layer on Ag nanoparticles can also enhance the surface plasmon resonance (SPR) absorption of Ag in long wavelengths. The mechanisms involved in shifts and broadening of SPR peaks have been explained detailedly. The effect of annealing process on SPR of Ag and photoelectric properties of AZO/Ag/AZO films can be also discussed. It is shown that the SPR peak of 664 nm only appears in AZO/Ag (5 s)/AZO film and no SPR peaks are found in annealed AZO/Ag/AZO films. The AZO/Ag (20 s)/AZO film annealed at 300 °C shows a great figure of merit (\(F_{\text{TC}}\)) of 4.8 × 10−2 Ω−1 because of high visible optical average transmittance of 85% and low sheet resistance (\(R_{\text{S}}\)) of 4.1 Ω/sq. The overall results reveal that annealing process can improve the electrical property of film and may not be able to promote the SPR of Ag nanoparticles, especially when AZO top layer is added. The introduction of Ag nanoparticles in AZO/Ag/AZO films should be very effective for improving the SPR or photoelectric properties of films depending on deposition conditions and annealing process.