SiO2 passivation effect on the hydrogen adsorption performance of a Pd/AlGaN-based Schottky diode

In this work, the comprehensive study of the hydrogen adsorption effects on the Pd/AlGaN-based MOS Schottky diode with SiO2 passivation is demonstrated. Hydrogen sensing performance of the proposed device is significantly enhanced with the insertion of SiO2 layer. The MOS diode exhibits a maximum sensing response value of 3.3 × 105 at 70 °C under a 1% H2/air gas. Additionally, the operating temperature for the maximum sensing response is decreased from 150 °C to 70 °C with the insertion of SiO2 layer. Moreover, the lowering of Schottky barrier height is 230 (200) meV for the MOS (MS) diode at room temperature. The hydrogen adsorption effect also largely influence the effective Richardson's constant. Furthermore, the transient-state experiments reveal that the MOS Schottky diode exhibits an activation energy of 14.1 kJ/mol which is lower than the MS Schottky diode (25 kJ/mol). Therefore, hydrogen sensing performance of the AlGaN-based Schottky diode can be significantly enhanced with the SiO2 passivation on the AlGaN surface.