Investigation of hydrogen-sensing properties of Pd/AlGaAs-based Schottky diodes

The hydrogen response characteristics and sensing properties or catalytic Pd/Al_0.3Ga_0.7As metal-oxide-semiconductor (MOS) and metal-semiconductor (MS) Schottky diodes are systematically studied. The effects of hydrogen adsorption on device performances such as the current-voltage characteristics, sensitivity, barrier height variation, heat of adsorption, and transient response are investigated. The studied devices can be operated under very wide hydrogen concentration regimes with remarkable hydrogen-sensing properties. Particularly, at an extremely low hydrogen concentration of 15 ppm H₂/air, both steady-state and transient responses at room temperature can be detected. In addition, under the presence of oxide layer in the studied MOS device, a larger change of barrier height and higher hydrogen response are observed. In addition, according to the van´t Hoff equation, the initial values of heat adsorption for Pd/semiconductor and Pd/oxide interface are calculated as 7.29 and 49.6 KJ/mole, respectively.