Remote sensing system for hydrogen using GaN Schottky diodes

The characteristics and operation of a GaN Schottky diode-based remote sensing system for hydrogen is described. The detection mechanism is a change in effective barrier height of the Pt or Pd contact on the GaN in the presence of even 600 ppm of H-2 This translates to a change in forward current at fixed bias voltage or a change in voltage across diode at fixed bias current, which means a change in impedance. The change in sensor impedance is amplified and the signal is transmitted at 916 MHz to a remote receiver base station. The base station response can be set to many possibilities, including alarms for signals above a particular threshold. The sensor Output increases with ambient temperature due to increased cracking efficiency of the hydrogen on the Pt or Pd surface. (c) 2004 Elsevier B.V. All rights reserved.