Tunability of Surface Plasmon Resonance Peaks in CsI:Ag Films by Growth Conditions

The manuscript reports the optical, structural, and morphological properties of thin films of CsI:Ag composites fabricated under various conditions by thermal evaporation method on glass substrates. The absorption spectra of these films show strong surface plasmon resonance (SPR) absorption peak/s. In samples with spherical silver nanoparticles, position of SPR peaks revealed red shift that was due to the increase the particle size of silver. Also, appearance of a new SPR peak was detected towards higher wavelengths due to the proximity effect, i.e., due to decrease in the interparticle distance between the silver nanoparticles. In contrast, the thin films with silver nanorods exhibited typical two SPR peaks assigned to higher and lower frequencies of visible spectrum. The aspect ratio of the nanorods showed an increasing trend with increase in film thickness. Results of this manuscript show how to achieve tunability of SPR peaks by varying the growth condition and film thickness.