A comparative study on capacitance and conductance-voltage response of titanium dioxide based MOS hydrogen sensor

Abstract

This paper deals with the gas sensing properties of palladium-gate MOS hydrogen gas sensor. The palladium-gate MOS gas sensor was fabricated on p-type <111> Si wafer having resistivity 3 to 5 ohm.cm.. The wafer was properly cleaned using standard cleaning procedures used in silicon technology.The structure of the device was completed by evaporating titanium dioxide over silicon wafer and subsequent palladium front with aluminium back metallization. The capacitance and conductance vs gate bias voltage characteristics of the fabricated device have been studied upon exposer to H2 in Ar atmosphere. The fabricated MOS capacitor with TiO2 as an insulator shows a significant change in capacitance and conductance with parallel shift in peak conductance position at room temperature, when exposed to H2 gas at various concentrations starting from 1 to 4% in Ar ambient with measurement frequencies 1 MHz and 100 kHz.