Effect of hydrogen exposure on the interface state density in titanium dioxide based MOS gas sensor

Abstract

Mechanism of the formation of hydrogen induced interface states at the Si/TiO2 interface has been investigated by conductance measurement of metal oxide semiconductor gas sensor. The conductance voltage response of the fabricated MOS capacitor has been studied upon exposure to hydrogen in argon ambient. The fabricated MOS device is sensitive to hydrogen (1-3%) at room temperature. The interface state density (Nit) is determined from the G-V curve, using a bias scan conductance method at fixed frequency. It is observed that, change in conductance is better at lower frequencies, which may be due to the balanced communication of interface traps with valance and conduction band of silicon substrate. Further it has been concluded that, present investigation provides a method for more accurate calculation of hydrogen induced interface traps in such device.