Palladium and platinum thin films for low-concentration resistive hydrogen sensor: a comparative study

In this study, palladium (Pd) and platinum (Pt) thin films are prepared via RF sputtering method with approximately 2 nm thicknesses on quartz substrates. Temperature-dependent resistances of Pd and Pt thin films are investigated at a temperature range from 30 to 130 degrees C. The results show that the resistance is directly proportional to temperature. The sensing properties of Pd and Pt thin films have been investigated depending on temperature and hydrogen concentration. It is found that Pt thin film shows higher sensitivity and lower limit of detection than Pd film, but the advantages of Pd thin film sensor are lower response time and unresponsive to the presence of oxygen compared to Pt thin film. The sensing mechanisms of Pd and Pt thin films are explained with continuous resistive H-2 sensor type and surface scattering phenomenon, respectively. The response and recovery times of the films are decreased with rising H-2 concentration and temperature.