Surface plasmon resonance technique applied to measurement of Ag2O thin films

JESICA M. J. SANTILLÁN; LUCÍA B. SCAFFARDI; DANIEL C. SCHINCA ; FABIÁN A. VIDELA

Lima

Congreso; VII RIAO – X OPTILAS 2010; 2010

VII RIAO – X OPTILAS

There is a continuing need for measuring nanometric film thicknesses for a wide variety of industrial and scientific purposes. Kretschmann type sensors are well known multilayer nanometric sensing devices. This paper is devoted to the study of specific characteristics of the reflectivitycurves in a particular Kretschmann design for determining silver oxide thickness grown on top of a thin silver film by direct oxidation at the expense of a decrease in the initial silver thickness.The dependence of these relevant characteristics with silver oxide thickness may be represented by different continuous functions defined for successive ranges that can be used as calibration curves. The particular characteristics of the reflectivity curves of this multilayer structure are studied for both p- and s-wave polarization as a function of the incidence angle. In the former, surface plasmon resonance (SPR) dip position as well as its FWHM depends strongly on silver oxide thickness. For s-wave polarization, a broad dip due to optical waveguide mode couplingis observed for angles larger than the total internal reflection (TIR) angle when sufficiently large silver oxide thickness are studied. Besides, reflectivity at fixed angles for both polarizations was studied as a function of silver oxide layer. Taking into account all these features, a measurementprotocol is proposed for determining silver oxide thickness when a 45 nm initial silver film is gradually converted into silver oxide by exposure to an oxygen rich atmosphere.