Browsing by Author "Erkovan, Mustafa"

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Cd Dopant Effect on Structural and Optoelectronic Properties of TiO2 Solar Detectors
(Springer, 2021) Ilhan, Mustafa; Koc, Mumin Mehmet; Coskun, Burhan; Erkovan, Mustafa; Yakuphanoglu, Fahrettin
Al/n-Si/Ti1-xO2CdxO/Al photodiodes were produced using sol-gel and spin coating methods where CdO dopant was applied on different concentrations (x = 0.0; x = 0.01; x = 0.05; x = 0.10). Cd dopant effect upon structural, optical, photodiode and electrical properties was assessed. Scanning electron microscope and energy-dispersive spectra were used in the structural investigation. Optic properties were assessed using UV-Vis spectroscopy and bandgap energies of the photodiodes were calculated which were found to be between 3.25 and 3.36 eV. Increased bandgap energy was observed with increased CdO doping rate. Photodiode properties were assessed under varying daylight illuminations. Barrier height, ideality factor, dark current, linear dynamic rate, photosensitivity, photoresponsivity of the photodiodes were calculated. Electrical properties of the Al/n-Si/Ti1-xO2CdxO/Al photodiodes were calculated where conductance-voltage and capacitance-voltage plots were obtained. Corrective conductance-voltage and corrective capacitance-voltage graphs confirm that the electrical properties of the photodiodes depend on AC signal frequency. Frequency-dependent electrical characteristics were attributed to the density of interface states which were found to be between 10(11) and 10(12). Decreased density of interface state was found for increased AC signal frequency.
Effect of Heat Treatment on Magnetic Properties of Nanocomposite Nd-Lean Nd7Fe73b20 Ribbons
(Springer, 2021) Caglar, Seyit; Kilicaslan, M. Fatih; Atasoy, Ahmet; Tiryaki, Hasan; Erkovan, Mustafa; Hong, Soon-jik
In this work, we explored the effect of heat treatment on high boron and Nd-lean content magnetic Nd7Fe73B20 nanocomposite materials via vibration sample magnetometer (VSM), X-ray diffraction, differential thermal analysis (DTA), and scanning electron microscope (SEM). The Scherer formula was employed to estimate the effect in the crystal size of the heat treatment on high boron and Nd-lean content magnetic Nd7Fe73B20 nanocomposite materials. We heat-treated samples in different conditions to obtain optimum magnetic properties. Our high-throughput fabrication strategy allows us to elucidate the possibility of obtaining Nd-lean nanocomposite NdFeB magnet in terms of the melt-spinning. We evaluated the influence of heat treatment on the Nd-lean NdFeB/alpha-Fe nanocomposite magnets produced by melt-spinning. Here, in the heat-treated ribbon at 750 degrees C for 30 min, we obtained a combination of coercivity of 450 Oe, a high-saturation magnetization of 232 emu/g in the heat-treated ribbon at 650 degrees C for 30 min, which surpasses most traditional nanocrystalline magnets based on Fe-Co and pricey. The results we present here are expected to serve as a guideline for designing new magnets for industrial applications.
Platinum-Nickel Alloy Thin Films for Low Concentration Hydrogen Sensor Application
(Elsevier Science Sa, 2022) Kilinc, Necmettin; Sanduvac, Senem; Erkovan, Mustafa
Hydrogen (H-2) gas sensing properties of platinum (Pt) -nickel (Ni) alloy thin films deposited on a glass substrate by sputter technique are investigated depending on alloy composition, temperature and H-2 concentration. The structural properties of Pt-Ni alloy thin films are characterized by XRD, SEM and EDS techniques. The amount of Ni atom in the alloy thin films is increased from 0% up to 60% and the H-2 sensing properties of the alloy thin film sensors are examined in the concentration range of 25-1000 ppm H-2. The results revealed that the H-2 sensing mechanism of the same thickness pure Pt and Pt-Ni alloy thin films could be explained with surface scattering phenomenon, and the Pt-79-Ni-21 alloy thin film exhibited the best sensing performance to H-2 at all measured temperature ranges. The limit of detection for Pt and Pt-Ni alloy thin films is calculated as lower than 1 ppm, and the response times of the films are decreased with rising H-2 concentration and temperature. (C) 2021 Elsevier B.V. All rights reserved.