Semiconductor Based Gas Phase Sensor for High Temperature and Robust Application





Figure above : Fabricated gas sensors (Schottky Diode)


In view of increased use of fuel cells as a new clean and viable energy source to replace petroleum, hydrogen sensors are strongly demanded to avoid hazardous explosion. High temperature operation and long term stability are important requirements for a gas sensor. GaN based materials are known as wide-bandgap semiconductors that show great promise for electronic devices operating at high temperatures. The response of Pt-circular Schottky diodes fabricated on undoped AlGaN/GaN high-electron-mobilitytransistor (HEMT) structure to hydrogen gas at various temperatures, ranging from 25°C to 200°C has been investigated [Figure above]. Both forward and reverse currents of the device increase when they are exposed to hydrogen gas. The time-transient characteristics showed the average current increment and decrement speed of 27.6 nA/sec and 17.6 nA/sec, respectively at a temperature of 200° C