Kirkendall assisted formation of SnO2–Ag nanocomposite for plasmonic-based gas sensor

Abstract

Nano-composite layers of SnO2-Ag are produced after deposition of Sn1-xAgx alloy on a fused silica (FS) followed by thermal oxidation. Silver nano-particles are formed inside the SnO2 layer during segregation into Kirkendall voids. A plasmonic-based optical sensing effect is demonstrated for acetone and alcohol in the temperature range of 200–400 °C. Red- and blue-shifts in the position of the plasmon-resonance peak are monitored for different conditions of SnO2+Ag layer formation and gas exposure. A dynamical response of the SnO2 /Ag sensor to methane/air cycles is measured, and the sensitivity of the sensor as a function of the operation temperature and illumination is investigated. The concept of plasmonic-based SnO2 sensors is discussed having in mind two main phenomena: First, the ability of metallic nanoparticles to hold plasmonic resonances which depends on the dielectric properties of surrounding SnO2 layer and second, the possibility of space-limited heating of nanoparticles and the neighbouring region with light, and in this way to control the chemisorption of oxygen on the sensor’s surface.