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.