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 Al 0.24Ga0.76As Schottky layer from oxidizing and to reduce the Fermi level pinning effect. Experimentally, a high sensitivity SJ value of 275.8 μA/mm·ppm H2/air can be obtained at a hydrogen concentration of 14 ppm H2/air. Even at a very low hydrogen concentration (≤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 τa 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.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)