Selective hydrogen detection of Pd/AlGaN/GaN HEMT-type sensors by temperature sweep operation

We have demonstrated the selective hydrogen gas detection of Pd/AlGaN/GaN high electron mobility transistors-based hydrogen sensors by the temperature sweep operation. The sensitivity-temperature spectra of the Pd/AlGaN/GaN HEMT hydrogen sensors in the range of 30°C to 350°C were measured in hydrogen, methane and propane with various concentrations of diluted with nitrogen. It is found that the different gases have the characteristic sensitivity-temperature spectra with the different peak positions, which is due to the decomposition temperature of each gas. The maximum sensitivities to hydrogen and propane are obtained at about 230°C and 310°C, respectively. The temperature sweep detection is very useful technique for the selective gas detection for the Pd/AlGaN/GaN HEMT-based gas sensors.