Sensing behavior and mechanism of titanium dioxide-based MOS hydrogen sensor

A Pd/TiO2/Si MOS sensor (Pdtisin sensor) is proposed for the detection of hydrogen gas. The sensor is fabricated on a p-type 〈1 1 1〉 silicon wafer having resistivity of 3–6 Ω cm. The thickness of TiO2 in this structure is about 600 nm. The capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics of the device is observed on the exposure of hydrogen gas at room temperature. The mechanism of hydrogen sensing of titanium dioxide-based MOS sensor (MOS capacitor) has been investigated by evaluating the change in flat-band voltage (VFB) and fixed surface state density of the device in presence of hydrogen gas. The device exhibits very large parallel shift in C–V as well in G–V characteristics. The possible mechanism on Pd/TiO2 and TiO2/Si surface in presence of hydrogen gas has been proposed. The response and recovery time of the device is also measured at room temperature.