Infrared reflectivity of Cox(SiO2)1-x (x ~ 0.85, 0.55, 0.38) granular films on SiO2 glass substrates

MASSA, N. E.; DENARDIN, J. C.; SOCOLOVSKY, L. M.; KNOBEL, M.; CRUZ, F. P. L.; ZHANG, X.

Solid State Communications

Elsevier Ltd.

Año: 2007 vol. 141 p. 551 - 554

0038-1098

We report the infrared specular reflectivity of Cox(SiO2)1−x (x 0.85, 0.55, 0.38) films on SiO2 glass spanning from a metal-like to insulating behavior. While films for x 0.85 show carrier metallic shielding and hopping conductivity, for x 0.65 and lower concentrations, the nanoparticles’ number and size promote a localization edge near the highest longitudinal optical frequency. Such an edge is associated with a reflectivity minimum and a higher frequency band connoting strong electron–phonon interactions, carrier phonon assisted hopping, and polaron formation. Optical conductivity fits with current polaron models provide grounds toward a microscopic understanding of transport properties in these as-prepared granular films.