Hydrogen-induced Dipoles and Sensing Principles of Pt-Ti-O Gate Si-MISFET Hydrogen Gas Sensors

AbstractDistribution of hydrogen-induced dipoles in platinum-titanium-oxygen (Pt-Ti-O) gate structures of Si-MISFET hydrogen gas sensors has been observed by H-specific 1H(15N,αγ) 12C nuclear reaction analysis (NRA). The sheet number of hydrogen-induced dipoles under N2-diluted 1% H2 atmosphere @50°C is estimated as 2.2x1014/cm2. The averaged vertical components of dipole-moments is estimated as 82.5D, if the relative dielectric constant of modified TiOx layer and the sensing amplitude ΔVg (V) are assigned by 114 and 624.4mV. We have found that the hydrogen-induced dipoles are generated in Pt-side modified TiOx layer, and also localized around specific thick pathway of the corridor originated from platinum grain-boundaries