Hydrogen Sensing Characteristics of Porous Pd/SiO2/GaN Schottky Diode

In this work, the porous Pd/SiO₂/GaN Schottky diode was fabricated by thermal evaporation (TE) for hydrogen sensing. The current-voltage (I-V) characteristics of the studied device were measured under hydrogen concentrations of 15 - 9970 ppm H₂/air and temperatures of 303 - 515 K. Furthermore, the hydrogen sensing performances of this device were investigated via the steady-state and transient detections. From experimental results, the studied device demonstrated excellent sensing performances with low detection limit (about ppb level), wide detection range (15 -9970 ppm), high sensitivity, and fast response and recovery rates (within several seconds for detection of 9970 ppm H₂/air). For the detection of 15 ppm at 423 K, the relative sensitivity even reached to 490%. In addition, the relative sensitivity was increased as either the hydrogen concentration or the detection temperature was incresaed. As compared with the dense structured device, the porous structured Pd/ SiO₂/GaN Schottky diode exhibited more superior sensing characteristics, especially at low hydrogen concentration with a relatively high sensitivity.