Production of metal oxide semiconductor materials and preparation of quartz crystal microbalance humidity sensors

In this study, undoped and Sn doped ZnO nanodust samples doped with different concentrations (0,1%, 1%, and 2%) have been prepared by Sol-gel method. The structural, electrical, optical, surface and humidity sensing properties of the samples have been characterized using different analysis techniques and the effect of doping on these properties have been investigated. The crystalline structures and surface morphology of the produced nanostructures were analyzed by X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM), respectively. X-Ray diffractometer measurements revealed that all the obtained samples were hexagonal wurtzite and polycrystalline structure. When the difraction patterns of all samples are investigated, it has been observed that the peak which has maximum intense is the peak belonging to (101) plane. Average grain size values, size of the crystallites and lattice constants of the samples were calculated. Besides, the electrical properties of the samples were investigated by using 2-probe method. Using the variations of electrical conductivities with temperature of the samples, the activation energies for low and high temperature regions were calculated. The UV-VIS spectrophotometer used to examine optic properties of the samples. The optical absorption studies reveal that the transition is direct with band gap energy values between 3,24 ? 3,28 eV. During the investigation of the sensor characteristics of ZnO nanostructures, the method of Quartz Crystal Microbalance (QCM) has been used. Sensor characteristics of synthesized undoped and Sn doped ZnO nanostructures, as a dependent upon the changes of frequency, have been researched in the changing humidity circumstances. Consequently, the usability of the undoped and Sn doped ZnO nanodust samples in the humidity sensor applications was proved.Keywords: Sensors, Humidity Sensors, Quartz Crystal Microbalance, QCM, Semiconductors, Zinc Oxide