Ga doped ZnO thin films deposited by RF sputtering for NO2 sensing.

Ga doped ZnO thin films have been deposited by Radio-Frequency (RF) magnetron sputtering on fused silica substrates. The structural analysis of the n-type sensitive material showed a preferential orientation in the [001] direction. The microstructure of the thin film indicated an increasing grain size with the increase of the thicknesses. The micro sensor platforms have been fabricated with ZnO:Ga thin film deposited using a reliable stencil mask onto interdigitated electrodes containing micro-hotplates. The as fabricated micro sensor allowed to sense sub-ppm concentration (500 ppb) of nitrogen dioxide under cycled temperature mode. This system revealed promising sensing performance with a response R/R0 up to 18 at low temperature step (50 °C).