Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 6Citation - Scopus: 6Experimental and Density Functional Theory Study on Humidity Sensing Properties of Copper Phthalocyanine (cupc)(IOP Publishing, 2019) Farzaneh, Amir; Okur, Salih; Okur, Salih; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe quartz crystal microbalance (QCM) technique was applied to investigate humidity sensing properties of a copper phthalocyanine (CuPc) thin film prepared by drop cast method. The humidity adsorption and desorption kinetics of (CuPc) thin film was evaluated. The QCM and electrical measurements results showed that humidity sensing properties of CuPc is very sensitive to humidity changes and reversible adsorption/desorption performance which is an indicative of a good humidity sensor even at room temperature. Reproducible experimental results indicated that CuPc thin films have an abundant potential for humidity sensing applications at ambient temperature. According to the first-principle density functional theory calculations, the promising humidity sensing properties of CuPc can be attributed to the considerable charge transfer from the water molecule into Cu atom.Article Citation - WoS: 5Citation - Scopus: 4The Effect of Annealing Temperature on the Optical Properties of a Ruthenium Complex Thin Film(Elsevier Ltd., 2016) Ocakoğlu, Kasım; Okur, Salih; Aydın, Hasan; Emen, Fatih Mehmet; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe stability of the optical parameters of a ruthenium polypyridyl complex (Ru-PC K314) film under varying annealing temperatures between 278 K and 673 K was investigated. The ruthenium polypyridyl complex thin film was prepared on a quartz substrate by drop casting technique. The transmission of the film was recorded by using Ultraviolet/Visible/Near Infrared spectrophotometer and the optical band gap energy of the as-deposited film was determined around 2.20 eV. The optical parameters such as refractive index, extinction coefficient, and dielectric constant of the film were determined and the annealing effect on these parameters was investigated. The results show that Ru PC K314 film is quite stable up to 595 K, and the rate of the optical band gap energy change was found to be 5.23 × 10- 5 eV/K. Furthermore, the thermal analysis studies were carried out in the range 298-673 K. The Differential Thermal Analysis/Thermal Gravimmetry/Differantial Thermal Gravimmetry curves show that the decomposition is incomplete in the temperature range 298-673 K. Ru-PC K314 is thermally stable up to 387 K. The decomposition starts at 387 K with elimination of functional groups such as CO2, CO molecules and SO3H group was eliminated between 614 K and 666 K.Article Citation - WoS: 36Citation - Scopus: 38Humidity Sensing Properties of Cds Nanoparticles Synthesized by Chemical Bath Deposition Method(American Chemical Society, 2011) Demir, Ramazan; Okur, Salih; Okur, Salih; Zor, Muhsin; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThin films of CdS nanoparticles were synthesized by the chemical bath deposition (CBD) technique to investigate humidity response characteristics. The morphology and the crystal structure of CdS thin films were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The quartz crystal microbalance (QCM) technique was used to measure the water vapor adsorption and desorption rates of CdS thin films. The dynamic Langmuir model was used to analyze the kinetics of the moisture adsorption and desorption process under relative humidity (RH) between 17 and 85% RH. Our results indicate that CdS thin films have a great affinity to humidity at room temperature.Article Citation - WoS: 12Citation - Scopus: 16Humidity Adsorption Kinetics of a Trypsin Gel Film(Elsevier Ltd., 2012) Okur, Salih; Ceylan, Çağatay; Ceylan, Çağatay; Okur, Salih; 04.05. Department of Pyhsics; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis study focuses on the humidity adsorption kinetics of an isopropanol-induced and pH-triggered bovine pancreatic trypsin gel (BPTG). The BPTG was adsorbed on a gold coated Quartz Crystal Microbalance (QCM) substrate with a thickness of 376nm. The morphology of the film was characterized using Atomic Force Microscopy (AFM). QCM was used to investigate the humidity sensing properties of the BPTG film. The response of the humidity sensor was explained using the Langmuir model. The average values of adsorption and desorption rates between 11% RH (relative humidity) and 97% RH were calculated as 2482.5M -1s -1 and 0.02s -1, respectively. The equilibrium constant and average Gibbs Free Energy of humidity adsorption and desorption cycles were obtained as 133,000 and -11.8kJ/mol, respectively. © 2011 Elsevier Inc..Article Citation - WoS: 36Citation - Scopus: 36High-Mobility Pentacene Phototransistor With Nanostructured Sio2 Gate Dielectric Synthesized by Sol-Gel Method(Elsevier Ltd., 2010) Okur, Salih; Okur, Salih; Stathatos, E.; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyWe have fabricated a pentacene based phototransistor by employing a modified nanostructured SiO2 gate dielectric. The photosensing properties of the pentacene thin film transistor fabricated on n-Si substrate with nanostructured SiO2 as gate dielectric have been investigated. The photocurrent of the transistor increases with an increase in illumination intensity. This suggests that the pentacene thin film transistor behaves as a phototransistor with p-channel characteristics. The photosensitivity and responsivity values of the transistor are 630.4 and 0.10 A/W, respectively at the off state under AM 1.5 light illumination. The field effect mobility of the pentacene phototransistor was also found to be 2.96 cm2/Vs. The nanostructured surface of the gate possibly is the cause of the high-mobility value of the phototransistor due to light scattering from the increased surface area. Crown Copyright © 2009.Article Citation - WoS: 12Citation - Scopus: 15Local Oxidation Nanolithography on Hf Thin Films Using Atomic Force Microscopy (afm)(IOP Publishing Ltd., 2009) Büyükköse, Serkan; Okur, Salih; Okur, Salih; Aygün, Gülnur; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyWell controlled Hf oxide patterns have been grown on a flat Hf thin film surface produced by the dc magnetron sputtering method on Si and SiOx substrates. These patterns have been created by using the technique of semi-contact scanning probe lithography (SC-SPL). The thickness and width of the oxide patterns have been measured as a function of applied voltage, duration and relative humidity. There is a threshold voltage even at 87% humidity, due to insufficient energy required to start the oxide growth process for a measurable oxide protrusion. Electrical characterization was also performed via the I-V curves of Hf and HfOx structures, and the resistivity of HfO x was found to be 4.284 × 109 Ω cm. In addition to the I-V curves, electric force microscopy and spreading surface resistance images of Hf and HfOx were obtained.Article Citation - WoS: 3Citation - Scopus: 3Mgb2 Superconducting Thin Films Grown by Magnetron Sputtering(National Institute of Optoelectronics, 2007) Ulucan, Savaş; Okur, Salih; Okur, Salih; Özyüzer, Lütfi; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study, we report the growth and properties of MgB2 thin films on polycrystalline Al2O3 substrates. A composite MgB2 target was produced by MgB2 and Mg powder mixing, using a hot pressing technique. MgB2 thin films were grown on Al 2O3 substrates by d.c. magnetron sputtering, without heating the substrate. To enhance the superconducting properties of the as-grown films and to increase the crystal quality, an ex-situ anneal process was applied. The crystal structure of the thin films was determined by X-ray diffraction. The resistivity versus temperature of the deposited MgB2 thin films was studied to examine the transition temperatures of the films under various magnetic fields. The effects of the annealing temperature and annealing time on the electrical properties of MgB2 thin films are revealed.Conference Object Citation - WoS: 6Citation - Scopus: 9Sub-Bandgap Optical Absorption Spectroscopy of Hydrogenated Microcrystalline Silicon Thin Films Prepared Using Hot-Wire Cvd (cat-Cvd) Process(Elsevier Ltd., 2006) Göktaş, Oktay; Işık, Nebile; Okur, Salih; Güneş, Mehmet; Carius, Reinhard; Güneş, Mehmet; Finger, Friedhelm; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyHydrogenated microcrystalline silicon (μc-Si:H) thin films with different silane concentration (SC) have been prepared using the HW-CVD technique. Dual beam photoconductivity (DBP), photothermal deflection spectroscopy (PDS), and transmission measurements have been used to investigate the optical properties of the μc-Si:H films. Two different sub-bandgap absorption, α(hν), methods have been applied and analyzed to obtain a better insight into the electronic states involved. A good agreement has been obtained in the absorption spectrum obtained from the PDS and DBP measurements at energies above the bandgap. Differences between PDS and DBP spectra exist below the bandgap energy where DBP spectra always give lower α(hν) values and show a dependence on the SC. For some films, differences exist in the α(hν) spectra when the DBP measurements are carried out through the film and substrate side. In addition, for some films, there remains fringe pattern left on the spectrum after the calculation of the fringe-free absorption spectrum, which indicates structural inhomogeneities present throughout the film.Conference Object Citation - WoS: 8Citation - Scopus: 9Diffusion Length Measurements of Microcrystalline Silicon Thin Films Prepared by Hot-wire/Catalytic Chemical Vapor Deposition (hwcvd)(Elsevier Ltd., 2006) Okur, Salih; Güneş, Mehmet; Güneş, Mehmet; Okur, Salih; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyHydrogenated microcrystalline silicon (μc-Si:H) films prepared by using the hot-wire/catalytic chemical vapor deposition (HWCVD) technique at low substrate temperatures between 185 °C and 220 °C with different silane concentrations (SC) were investigated using steady-state photocarrier grating (SSPG) and the steady-state photoconductivity methods (SSPC). Crystalline volume fractions (IC RS) obtained from Raman spectroscopy change from 0.22 to 0.77. The diffusion length (LD) is measured at generation rates between G = 1019 and 1021 cm- 3 s- 1. LD changes from 27 nm to 270 nm, with maximum values around SC = 5%. The dependence of LD on SC is similar to that observed for similar quality microcrystalline silicon films prepared using the VHF-PECVD technique. The grating quality factor, γ0, drops from about 0.9 to 0.5 after transition to the microcrystalline regime as indication of scattering from surface patterns.Article Citation - WoS: 13Citation - Scopus: 12Mgb2 Superconducting Thin Films Sequentially Fabricated Using Dc Magnetron Sputtering and Thermionic Vacuum Arc Method(Elsevier Ltd., 2007) Okur, Salih; Kalkancı, M.; Okur, Salih; Ekem, Naci; Tanoğlu, Metin; Balbağ, Zafer; Musa, G.; Tanoğlu, Metin; 04.05. Department of Pyhsics; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this work, we discuss fabrication and characterization of MgB2 thin films obtained by sequential deposition and annealing of sandwich like Mg/B/Mg thin films on glass substrates. Mg and B films were prepared using DC magnetron sputtering and thermionic vacuum arc techniques, respectively. The MgB2 thin films showed superconducting critical transition at 33 K after annealing at 650 °C.