Hydrogen Gas Micro Sensor Based on SiO₂ and TiO₂ Systems

Abstract

Comparative study of the sensing properties of the two systems Pd/SiO₂/Si and Pd/TiO₂/Si for the hydrogen gas, has been done. Two samples of both the systems were fabricated and their C-V characteristics were studied without and with the exposure of hydrogen gas in nitrogen ambient. In both the cases, it is found that upon exposure to hydrogen there is reduction in capacitance value and simultaneously flat-band voltage, V_FB, also changes. These changes are attributed to the change in work function of the gate metal as well as the interface states. Though, the sensing mechanism in both the MOS structures is almost similar, but higher polarizability of TiO₂ lattice and more diffusibility of hydrogen in TiO₂ results larger change in capacitance in TiO₂ system as compared to SiO₂ system, Hence, Pd/Ti O₂/Si system is more suitable for hydrogen gas detection.

Indexing terms:

• Hydrogen gas micro sensor
• MOS devices