Nanocomposites and nanomaterials

Humidity sensor element based on oxidized porous silicon – reduced graphene oxide hybrid structures
I.B. Olenych1, Yu.Yu. Horbenko2, L.S. Monastyrskii1, O.I. Aksimentyeva2, Ya.V. Boyko1
1 Electronics and Computer Technologies Department, Ivan Franko National University of Lviv, 50 Dragomanov Str., Lviv-79005, Ukraine
E-mail: iolenych@gmail.com
2 Chemistry Department, Ivan Franko National University of Lviv, 6 Kyrylo and Mefodiy Str., Lviv-79005, Ukraine 

Nanostructured semiconductors with an ultra-high specific surface are extremely promising in the field of sensor electronics. In particular, nanostructures of porous silicon (PS) are widely used as sensitive elements of gas sensors [1]. The combination of the PS with other nanoparticles can increase the sensitivity and selectivity of sensors. Given this, an up-and-coming technology is the deposition of graphene nanostructures on the PS layer [2, 3]. The local electric field of adsorbed gas molecules causes changes in the electrical conductivity of both PS nanostructures and graphene. 
In this work, oxidized PS–reduced graphene oxide (rGO) hybrid structures were created to study their sensory properties. We have found that the obtained hybrid structures show a decrease in resistance and an increase in capacitance in AC mode with increasing relative humidity. Dependence of the sensing ability on relative humidity and kinetic characteristics of resistive and capacitive sensor elements were studied to evaluate the sensory properties of obtained structures. The obtained results demonstrate high potential applications of the oxidized PS–rGO hybrid structures in humidity sensors. 

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