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Surface plasmon resonance, photoluminescence and surface enhanced Raman scattering behaviour of Ag/ZnO, ZnO/Ag and ZnO/Ag/ZnO thin films
摘要： The surface plasmon resonance (SPR) of Ag thin films in ZnO/Ag, Ag/ZnO bilayers and ZnO/Ag/ZnO multilayers produced by vacuum thermal evaporation has been studied. The role of thickness of the individual layers in the range of 5-50 nm was investigated. Detailed studies were carried out by fixing the thickness of the plasmon active layer and varying the dielectric layer thickness and vice versa. These studies reveal that the SPR of Ag is very sensitive to the geometry of the structures and as a consequence it has a strong effect on the photoluminescence (PL) as well as Surface enhanced Raman Scattering (SERS) behaviour. The PL peak of 5 nm thickness pure ZnO films which was centred at around 370 nm, was red shifted at higher thickness of 50 nm. Further, this peak was blue shifted to 324 nm when a 5 nm thickness Ag layer is introduced underneath the ZnO layer. The SERS behaviour of these structures was tested using R6G as the analyte. The enhancement factor for a 5 nm thickness pure Ag film was found to be 5x103. The highest enhancement factor for ZnO/Ag, Ag/ZnO and ZnO/Ag/ZnO trilayer films was found to be 7.4x106, 4.4x105 and 8.9x104, respectively.
关键词： surface plasmon resonance,surface enhanced Raman scattering,photoluminescence,Ag-ZnO multilayer films
更新于2025-09-09 09:28:46
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Structural and Photoluminescence Properties of nc-SiOx:H/a-SiOx:H Multilayer Films Deposited at Low Temperature by VHF-PECVD Technique
摘要： Hydrogenated nanocrystalline silicon oxide/hydrogenated amorphous silicon oxide (nc-SiOx:H/a-SiOx:H) multilayer films were fabricated using very-high-frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) technique by alternate deposition of nc-SiOx:H and a-SiOx:H at a low substrate temperature of 220 °C. The effects of the amount of oxygen incorporation in the nc-SiOx:H sublayers on the structural and photoluminescence (PL) properties of nc-SiOx:H/a-SiOx:H multilayer films were investigated by transmission electron microscopy, Raman scattering, UV–VIS-NIR absorption spectra, steady and time-resolved PL spectra. As the amount of oxygen incorporation increases, the crystalline volume fraction of multilayer films decreases, while the intermediate-range order of multilayer films firstly increases and then decreases. Strong room temperature PL has been observed in the multilayer films and the correlation between structural and PL properties is discussed. This low-temperature procedure for fabricating nc-SiOx:H/a-SiOx:H multilayer films can provide powerful impetus for the further development of optoelectronic devices based on Si-NCs.
关键词： Hydrogenated nanocrystalline silicon oxide,VHF-PECVD,Photoluminescence,Multilayer films
更新于2025-09-04 15:30:14
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Preparation of ZnO Nanoparticles Under Ultrasonic Irradiation and Photocatalytic Performance of ZnO Nanoparticles Multilayer Films
摘要： Zinc oxide nanoparticles were synthesized by the reaction of an aqueous-alcoholic solution containing zinc nitrate hexahydrate and sodium hydroxide under ultrasonic irradiation at room temperature. The crystallinity, morphology and optical property of ZnO nanoparticles were examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV-visible spectrophotometer. Zinc oxide nanoparticles multilayer films were prepared dipping glass slide, which had been cleaned with a piranha solution, into a ZnO solution by ultrasonic irradiation. The ZnO nanoparticles multilayer films were evaluated as a photocatalyst in the photocatalytic degradation of organic dyes, such as methylene blue, methyl orange and rhodamine B, under ultraviolet light at 254 nm.
关键词： Multilayer films,Photocatalytic activity,Zinc oxide nanoparticles,Organic dyes,UV-visible spectrophotometer
更新于2025-09-04 15:30:14