Nanoyapılı Pt ve Pt-Ag alaşımlarının üretimi, karakterizasyonu ve hidrojen gaz algılama özelliklerinin incelenmesi

This thesis presented hydrogen (H2) sensing properties of platinum (Pt) and platinum-silver (Pt-Ag) thin films. Pt and PtAg films were deposited on glass substrate by magnetron sputter technique. The Pt thin films with different thickness (2-50 nm) were prepared using RF sputtering method. The thicknesses of the films were controlled by a piezoelectric sensor placed in sputter system at the same time of coating process. On the other hand in this study, 3 nm PtxAg1-x (x: 0.95, 0.90, 0.80 and 0.50) thin films were coated by co-sputtering technique. The structural properties of Pt and PtAg alloy films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) techniques. Hydrogen sensing properties of the Pt and PtAg films were investigated depending on film thickness, temperature and concentration. Temperature dependent resistances and the gas measurements of the Pt and PtAg thin films were studied under a dry air flow and hydrogen ambient at a temperature range from 30 °C to 200 °C. Thus the best working performances of Pt and PtAg sensors were detected. The results showed that the resistance is directly proportional with temperature, and inversely proportional with the thickness of Pt thin film sensors. The H2 sensing properties of Pt thin film sensors were examined in the concentration range of 0.1 % - 1 % H2. Among the results for Pt thin films, it was revealed that the Pt thin film with 2 nm thickness exhibited the best sensing performance to H2 at 30 °C under dry air flow. The best response time was obtained at high temperatures for Pt thin film sensors. H2 sensitivity of PtAg sensors were also investigated in the concentration of 25 ppm - 1000 ppm H2. The resistances and the sensitivities of PtAg thin film sensors were increased with enhancing the temperature. Among the results for PtAg sensors, 3 nm Pt0.80Ag0.20 sensor showed the best sensitivity properties at 150 oC.