Dilute Hydrogen Sulfide Sensing Characteristics of a Pt/GaN Schottky Diode
The sensor studied in this paper contains four layers, which is showed in Figure 1 in detail. The Ohmic contact was formed by lift-off of e-beam evaporated Ti(200 Å)/Al(800Å)/ Ni(400Å)/Au(1000Å) and annealed at 850°C for 42 s under a flowing N2 ambient in a Premtek / ARTs 150. 100Å of Pt was deposited by e-beam evaporation to form Schottky contact as well as used as catalytic metal. Figure 2 shows three sets of Pt/GaN Schottky diode in different size and the size for the whole device is about 2×2mm. As the result of experiment, all of these three diodes are sensitive to H2S. Figure 3 shows real-time detection of 0.7ppm H2S in air. Figure 4 shows the relation between current change and concentration of H2S from 0.1-1ppm. All of the devices are tested in 200℃ and applied with 0.5ms width 1.5V pulse every second. With this Pt/GaN Schottky diode we can detect H2S down to 0.05pp.
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[iii] Jun Tamaki , Kengo Shimanoe, Yoshihiro Yamada, Yoshifumi Yamamoto, Morio Miura, and Noboru Yamazoe,” Dilute Hydrogen Sulfide Sensing Properties of Copper Oxide-Tin Oxide Thin Film Prepared by Low-Pressure Evaporation” Solid State Sensors and Actuators, 1997 International Conference