AlGaAs/InGaAs/GaAs Transistor-Based Hydrogen Sensing Device Grown by Metal Organic Chemical Vapor Deposition

概要

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By combining the advantages of a catalytic metal Pd with a high-performance AlGaAs/InGaAs/GaAs pseudomorphic high-electron-mobility transistor (PHEMT), an interesting hydrogen sensor is fabricated and demonstrated. For the proposed device, a 50 Å undoped GaAs cap layer is grown to prevent the Al0.24Ga0.76As Schottky layer from oxidizing and to reduce the Fermi level pinning effect. Experimentally, a high sensitivity $S_{J}$ value of 275.8 μA/mm$\cdot$ppm H2/air can be obtained at a hydrogen concentration of 14 ppm H2/air. Even at a very low hydrogen concentration (${\leq}4.3$ ppm H2/air) at 30°C, a significant current variation can be observed. In addition, a fast transient response is found. The adsorption time constant $\tau_{\text{a}}$ becomes only 2 s as the operating temperature is elevated to 160°C. Therefore, the proposed device reveals the promise for high-performance hydrogen sensor applications.
2006-02-15