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

NÉSTOR E. MASSA; JULIANO C. DENARDIN; LEANDRO M. SOCOLOVSKY; MARCELO KNOBEL; FERNANDO PABLO DE LA CRUZ; XIANG X. ZHANG

SOLID STATE COMMUNICATIONS

Elsevier

Lugar: New York; Año: 2007 vol. 141 p. 551 - 554

0038-1098

We report 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 promotes a localization edge near the highest longitudinal optical frequency. Such 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 ground toward a microscopic understanding of transport properties in these as prepared granular films