Fast highly-sensitive room-temperature semiconductor gas sensor based on the nanoscale Pt–TiO2–Pt sandwich

Abstract

Fast highly-sensitive room-temperature semiconductor gas sensor based on the nanoscale Pt-TiO 2 -Pt sandwich, Sensors and Actuators B: Chemical (2014), http://dx. AbstractDevelopment of fast highly-sensitive semiconductor gas sensors operating at room temperature, which would be compatible with semiconductor technology, remains a challenge for researchers.Here we present such sensor based on a nanoscale Pt-TiO 2 -Pt sandwich. The sensor consists of a thin (~30 nm) nanocrystalline TiO 2 layer with ~10 nm grains, placed between the bottom Pt electrode layer and top Pt electrode shaped as a long narrow (width w down to 80 nm) stripe. If we decrease w to ~100 nm and below, the sensor exposed to air with 1% H 2 exhibits the increase of response (R air / ) up to ~ 10 7 and decrease of the reaction time to only a few seconds even at room temperature. The sensitivity increase is due to a nontrivial non-ohmic effect, a sudden decrease (by three orders of magnitude) of the electrical resistance with decreasing w for w ~ 100nm. This non-ohmic effect is explained as a consequence of two nanoscale-related effects: the hydrogen-diffusion-controlled spatially-inhomogeneous resistivity of the TiO 2 layer, combinedPage 2 of 41 A c c e p t e d M a n u s c r i p t 2 with onset of the hot-electron-temperature instability when the tiny grains are subjected to high electric field.

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