Dielectric dispersion of rf Sputter-deposited SnO2, ZnO, WO3 thin films using surface plasmon resonance technique

Surface Plasmon Resonance (SPR) is a highly sensitive technique for investigating the dielectric and optical properties of dielectrics at metal-dielectric interface. In the present article, the dielectric properties of various wide band gap (WBG) semiconductor have been studied using SPR technique at different wavelengths. The metal oxide thin films of interest are tungsten oxide (WO₃), tin oxide (SnO₂) and zinc oxide (ZnO) which were deposited by rf magnetron sputtering under optimized growth conditions. Gold coated glass prisms have been utlilized to excite the surface plasmon waves at the metal-dielectric (air) interface. When metal oxide thin films are integrated with the surface of metal thin film, a significant shift in the SPR curve has been observed due to change in the propagation constant of Surface Plasmon Wave (SPW) at metal-dielectric interface. The optical and dielectric parameters of WBG thin films were estimated by fitting experimental SPR data with the Fresnel´s equations. SPR reflectance curves obtained using laser of various wavelengths were ultilized to determine the wavelength dispersion of the dielectric properties of these metal oxide thin films.