Co-sputtered Pd/SnO2:NiO heterostructured sensing films for MEMS-based ethanol sensors

Abstract

Here, we disclose the Pd-doped SnO2:NiO sensing films integrated on the microheaters by a facile co-sputtering method. The Pd content is controlled by the sputtering power, and thermal annealing at 500 °C in H2 is implemented to activate the hybrid Pd/SnO2:NiO film. The 20 nm-thick Pd/SnO2:NiO films with Pd sputtering power of 20 W exhibits significantly enhanced ethanol sensing performance, with the response of 12 to 50 ppm ethanol, low detection limit of <5 ppm, high selectivity, good stability and low device-to-device variation of <15%. The gas sensing property enhancement can be predominantly attributed to the Schottky barrier at Pd-SnO2 interface and the Pd-induced catalytic oxidation of ethanol. These results enable the fabrication of wafer-scale micro ethanol gas sensors with low energy dissipation using the entire Micro-Electrical-Mechanical System (MEMS) strategy.