Koksal Yildiz

Investigation of structural and electrical properties of Zirconium dioxide thin films deposited by reactive RF sputtering technique

ABSTRACT ZrO2 thin films with different thicknesses (400 nm, 500 nm, 600 nm) were deposited by reactive RF magnetron sputtering technique, on n-type Silicon (100) substrate at 200°C applying 125 W power ratin`g. The micro structural properties of thin films were obtained by Scanning Electron Microscope and it was observed that the films were grown successfully in the form of big grains formed by the accumulation of small particles. It was seen that the size of grains changed with the increase of film thickness. Energy-dispersive X-Ray spectroscopy was used to determine the chemical compositions of samples. The crystal structures of ZrO2 samples were analyzed by X-ray diffraction technique. In addition, the Current-Voltage and Capacitance-Voltage measurements were completed to investigate the electrical properties of samples.

Quenching media effects on martensitic transformation, thermodynamic and structural properties of Cu–Al–Fe–Ti high-temperature shape memory alloy

We investigated the effect of three different quenching medias on martensitic transformation, thermodynamic parameters, phase equilibria, microstructural properties and microhardness values of high-temperature Cu–13.2Al–5.1Fe–1.2Ti (mass%) shape memory alloy by means of differential scanning calorimetry, X-ray diffraction, optical microscopy, scanning electron microscopy and Vicker’s microhardness measurements. Thermal analysis indicated that the transformation temperatures and thermodynamic parameters of the alloy changed depending on quenching conditions and the transformation temperature range was proportional to the cooling rate. It was found that the step-quenching treatment improved the operation temperature of alloy. Structural analysis showed that the phase components of the alloy were not affected significantly by the quenching conditions, but elemental analysis also revealed that high cooling rate leads to very significant changes on chemical compositions of the phase components. From microstructural investigations, it was found that the microstructure of alloy included a great number of voids having different sizes and forms and also different precipitates grow in these voids. In particular, it was seen that the step-quenching process caused the formation of new voids in the microstructure. Vicker’s microhardness measurements revealed that the microhardness value of the alloy was not influenced markedly by the quenching treatments.

Influence of annealing time on the physical properties of reactively sputtered CuO thin film

Polycrystalline CuO thin film was deposited by reactive RF magnetron sputtering technique. The samples obtained from CuO film were annealed in air for different times. The structural, compositional and optical properties of unannealed and annealed samples were characterized. The SEM studies showed that the samples have a homogeneous surface morphology. All of the samples exhibited strong

Electron microscopy study of thermoelectric n-type Bi2(Te0.9Se0.1)3 film deposited by dc sputtering

(\bar{1}11)

Oxidation parameters determination of Cu–Al–Ni–Fe shape-memory alloy at high temperatures

(1¯11) diffraction peak and optical transmittance above 70%. As the annealing time was increased, the grain size increased and the optical band gap decreased.