Fabrication of ZnO/Au/prism-based surface plasmon resonance device for gas detection

Surface plasmon resonance (SPR) sensing devices have attracted interest both from a fundamental physics perspective and as higly sensitive devices for detecting small chemical and biological objects. In this work, we design SPR device using a modified Kretschmann configuration for gas detection. After gold coating on the flat surface of BK-7 semicylindrical prism, ZnO microstructures which work as sensitive layer, are formed on the gold film surface. The light reflectance is measured for various angles in order to observe the SPR spectra. Next, we measure the shift of SPR angle due to response of ZnO sensitive layer to CO2 gas. It is found that the absorption of gas molecules on the sensitive layer produces the shift of SPR spectra to the higher incident angle. The change of the light reflectance due to the gas response on the time-dependent characteristics is also studied.