Resistive Gas Sensor Based on Mesoporous MoS2 Films

Le résumé fourni par la source

Semiconducting mesoporous films with high specific surface area are of great interest for development of gaseous media sensors. In this work such sensors were fabricated using material synthesized on different substrates via chemical reaction between gaseous H2S and Mo vapor obtained by thermal evaporation. By X-ray photoelectron spectroscopy chemical composition of MoS2 was confirmed. By the use of scanning electron microscopy it was revealed that deposited on different substrates films consist of an array of crystallites of nanometer thickness and transversal dimensions of several hundreds of nanometers. MoS2 crystallites are oriented predominantly perpendicularly to substrate surface and spaced by distance of several dozens of nanometers. It was discovered that electrical resistivity of MoS2 decrease with increasing of air humidity and NH3 vapor concentration. Response profile has exponential time dependence and has two time constants. Characteristic rise times for NH3 vapor case are 0.9 and 17 s, and fall times– 1.2 and 29 s. In case of H2S vapor rise times are 4 and 45 s, and fall times– 1.25 and 42 s. Mechanisms of increasing in electrical conductivity with increasing air humidity and NH3 vapor concentrations are discussed.

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