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 x 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 Omega upon exposing to hydrogen gas at 200 degrees 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 1V, the response time is decreased by 15 s under the 1010ppm H(2)/air gas. Furthermore, based on the kinetic adsorption analysis the rate constant k(r) increases from 6.22 x 10(-1) to 1.54 s(-1) at 300 degrees C with exposing to 99.4 and 9660 ppm H(2)/air gases, respectively. Therefore, on the basis of the compatibility with AlGaN-based microwave devices, the studied Pd/AIGaN hydrogen sensor shows the promise for fabricating the on-chip wireless senor systems. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.