Temperature-dependent hydrogen sensing characteristics of a new Pt/InAlAs Schottky diode-type sensor

By combining the advantages of a catalytic Pt metal with an InAlAs material system, an interesting hydrogen sensor is fabricated and demonstrated. The Pt/InAlAs Schottky diode-type sensor exhibits high sensing performance toward hydrogen gas. A comparative study between forward and reverse biases is presented. A simple detection model is proposed to elucidate the hydrogen sensing behavior under forward and reverse biases. Thermionic emission (TE) and field emission (FE) exhibit considerable influences on the hydrogen sensing properties. Moreover, the temperature-dependent hydrogen detection characteristics are presented and studied. High sensor response is observed under reverse voltage, while large current variation is found under forward voltage. It is worth to note that this sensor shows a widespread reverse voltage-operating regime (0 to -5 V) with stable and flat sensing curves. The effective Schottky barrier height change and the series resistance variation, from the Norde plots, are -87.0 meV and -288 Omega, respectively, in 10,000 ppm H-2/air at 303 K. Based on the significant advantage of integration compatibility with InP-based electronic devices, the studied device reveals the promise in smart sensor and micro-electro-mechanical system (MEMS) applications. (C) 2007 Elsevier B.V. All rights reserved.