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Investigation of Pd/TiO2/Si MIS capacitor as hydrogen sensor

Sensor Review, Volume 35, Issue 1, January 2015.
Purpose The present study investigates the gas sensing capability of Pd/TiO2/Si MIS capacitor using capacitance versus gate voltage (C-V) response as a function of hydrogen gas concentration varying from 0.1 ppm to 2 ppm at 300 kHz frequency. Design/methodology/approach The objective is to fabricated a MIS capacitor sensor based on TiO2 thin film insulator deposited by sol-gel spin coating process. Gas sensing signal derived on exposure to hydrogen with concentration varying from 0.1 ppm to 2 ppm at different operating temperatures (room temperature to 1500C) was measured as variation in flat-band voltage in C-V characteristics of the MIS capacitor. Findings High sensitivity of the sensor is attributed to the large change of interface state charges because of the large surface to volume ratio of the nano-structured TiO2. The values of response time as well as the recovery time have also been estimated and are found to be comparable to that observed in the case of conventional MOS structure. Research limitations/implications The use of Si substrate restricts the performance of gas sensors to 200 °C as the Si substrate begins to show conductive nature. Originality/value This paper deals with a MIS capacitor gas sensor which replaces conventional insulating material by TiO2 and uses a high quality fabrication procedure for controlled growth of novel surface structure.

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