Metal nanoparticle embedded porous thin films prepared by oblique angle coevaporation

Using oblique angle coevaporation, the authors have successfully incorporated Ag nanoparticles into MgF2 porous films. The size of the embedded Ag nanoparticles and the porosity of MgF2 host increase with increasing vapor incident angle, resulting in a redshift in the plasmon resonant wavelength of the Ag nanoparticles. The optical properties of the composite films also depend on the ratio of MgF2 and Ag, the film thickness, and the host porosity. This method can be used to fine-tune the plasmon absorbance peaks of metal-insulator composite thin films, and have potential applications in optical devices and chemical and biological sensing. (c) 2008 American Vacuum Society.