Comprehensive study on hydrogen sensing properties of a Pd–AlGaN-based Schottky diode

In this work, the temperature dependences of a Pd/AlGaN Schottky diode-type hydrogen sensor are investigated. The effects of temperature on parameters such as breakdown voltage, response time, and series resistance are presented. Experimentally, under a fixed current bias of −2×10−5 A a reverse voltage response as high as 6 V is observed. The hydrogen adsorption effect also exhibits influences on the series resistance which is decreased by 18 Ω upon exposing to hydrogen gas at 200 °C. Besides, the ideality factor n shows a decreasing trend with the introduction of hydrogen gas. The voltage dependence on sensor performance is also studied. By increasing the voltage from 0.35 to 1 V, the response time is decreased by 15 s under the 1010 ppm H2/air gas. Furthermore, based on the kinetic adsorption analysis the rate constant kr increases from 6.22×10−1 to 1.54 s−1 at 300 °C with exposing to 99.4 and 9660 ppm H2/air gases, respectively. Therefore, on the basis of the compatibility with AlGaN-based microwave devices, the studied Pd/AlGaN hydrogen sensor shows the promise for fabricating the on-chip wireless senor systems.