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Article Citation - WoS: 53Citation - Scopus: 54Forward and Reverse Bias Current-Voltage Characteristics of Au/N-si Schottky Barrier Diodes With and Without Sno2 Insulator Layer(Elsevier, 2011) Gokcen, M.; Altindal, S.; Karaman, M.; Aydemir, U.The effects of interfacial insulator layer, interface states (N-ss) and series resistance (R-s) on the electrical characteristics of Au/n-Si structures have been investigated using forward and reverse bias current-voltage (I-V) characteristics at room temperature. Therefore, Au/n-Si Schottky barrier diodes (SBDs) were fabricated as SBDs with and without insulator SnO2 layer to explain the effect of insulator layer on main electrical parameters. The values of ideality factor (n), R-s and barrier height (Phi(Bo)) were calculated from ln(I) vs. V plots and Cheung methods. The energy density distribution profile of the interface states was obtained from the forward bias I-V data by taking bias dependence of ideality factor, effective barrier height (Phi(e)) and R-s into account for MS and MIS SBDs. It was found that N-ss values increase from at about mid-gap energy of Si to bottom of conductance band edge of both SBDs and the MIS SBD's N-ss values are 5-10 times lower than those of MS SBD's. An apparent exponential increase from the mid-gap towards the bottom of conductance band is observed for both SBDs' (MS and MIS) interface states obtained without taking R-s into account. (C) 2011 Elsevier B.V. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 3Fabrication of Cdsexte1-X Thin Films by Sequential Growth Using Double Sources(Elsevier, 2021) Demir, M.; Gullu, H. H.; Terlemezoglu, M.; Parlak, M.CdSexTe(1-x) (CST) ternary thin films were fabricated by stacking thermally evaporated CdSe and electron beam evaporated CdTe layers. The final structure was achieved in a stoichiometric form of approximately Cd:Se:Te = 50:25:25. The post-annealing processes at 300, 400, and 450 degrees C were applied to trigger the compound formation of CST thin films. The X-ray diffraction (XRD) profiles revealed that CdTe and CdSe have major peaks at 23.9 degrees and 25.5 degrees corresponds to (111) direction in cubic zinc-blend structure. Raman modes of CdTe were observed at 140 and 168 cm(-1), while Raman modes of CdSe films were detected at 208 and 417 cm(-1). The post-annealing process was found to be an effective method in order to combine both diffraction peaks and the vibrational modes of CdTe and CdSe, consequently to form CST ternary alloy. Transmission spectroscopy analysis revealed that CST films have direct band gap value of 1.6 eV.Article Citation - WoS: 3Citation - Scopus: 6Structural and Optical Properties of Thermally Evaporated Cu-Ga (cgs) Thin Films(Elsevier, 2018) Gullu, H. H.; Isik, M.; Gasanly, N. M.The structural and optical properties of thermally evaporated Cu-Ga-S (CGS) thin films were investigated by Xray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM) and optical transmittance measurements. The effect of annealing temperature on the results of applied techniques was also studied in the present paper. EDS results revealed that each of the elements, Cu, Ga and S are presented in the films and Cu and Ga concentration increases whereas S concentration decreases within the films as annealing temperature is increased. XRD pattern exhibited four diffraction peaks which are well-matched with those of tetragonal CuGaS2 compound. AFM images were recorded to get knowledge about the surface morphology and roughness of deposited thin films. Transmittance measurements were applied in the wavelength region of 300-1000 nm. Analyses of the absorption coefficient derived from transmittance data resulted in presence of three distinct transition regions in each thin films with direct transition type. Crystal-field and spin-orbit splitting energies existing due to valence band splitting were also calculated using quasicubic model.Article Citation - WoS: 13Electrochemical and Quantum Chemical Studies on Mitomycin and Adriamycin(Elsevier, 2003) Özalp-Yaman, S; Önal, AM; Türker, LIn-situ spectroelectrochemical redox behaviour of two prominent chemotherapeutic agents, mitomycin and adriamycin were studied at constant potential. AM 1 (UHF) type quantum chemical calculations on the neutral as well as radical anion and cation forms of mitomycin and adriamycin were performed. (C) 2003 Elsevier Science B.V. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 13Novel Pt(ii) Complexes Containing Pyrrole Oxime, Synthesis, Characterization and Dna Binding Studies(Elsevier, 2014) Erdogan, Deniz Altunoz; Ozalp-Yaman, SenizSince the discovery of anticancer activity and subsequent clinical success of cisplatin (cis-[PtCl2(NH3)(2)]), platinum-based compounds have since been widely synthesized and studied as potential chemotherapeutic agents. In this sense, three novel nuclease active Pt(II) complexes with general formula; [Pt(NH3)CI(L)] (1), [Pt(L)(2)] (2), and K[PtCl2(L)] (3) in which L is 1-H-pyrrole-2-carbaldehyde oxime were synthesized. Characterization of complexes was performed by elemental analysis, FT-IR, H-1 NMR and mass spectroscopy measurements. Interaction of complexes (1-3) with calf thymus deoxyribonucleic acid (ct-DNA) was investigated by using electrochemical, spectroelectrochemical methods and cleavage studies. The hyperchromic change in the electronic absorption spectrum of the Pt(II) complexes indicates an electrostatic interaction between the complexes and ct-DNA. Binding constant values between 4.42 x 10(3) and 5.09 x 10(3) M-1 and binding side size values between 2 and 3 base pairs were determined from cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies. (C) 2014 Elsevier B.V. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 12Design and Characterization of Tlinse2 Varactor Devices(Elsevier, 2011) Qasrawi, A. F.; Aljammal, Faten G.; Taleb, Nisreen M.; Gasanly, N. M.TlInSe2 single crystal has been successfully prepared by the Bridgman crystal growth technique. The crystal, which exhibits compositional atomic percentages of 25.4%, 25.2% and 49.4% for TI, In and Se, respectively, is found to be of tetragonal structure with lattice parameters of a=0.8035 and c=0.6883 nm. The crystals were used to design radio frequency sensitive varactor device. The temperature dependence of the current-voltage characteristics of the device allowed the calculation of the room temperature barrier height and ideality factor as 0.87 eV and as 3.2, respectively. Rising the device temperature increased the barrier height and decreased the ideality factor. This behavior was attributed to the current transport across the metal-semiconductor interface. The capacitance of the device is observed to increase with increasing voltage and increasing temperature as well. The temperature activation of the capacitance starts above 82 degrees C with a temperature coefficient of capacitance being 1.08 x 10 (3) K (1). Furthermore, the capacitance of the device was observed to increase with increasing frequency up to a maximum critical frequency of 4.0 kHz, after which the capacitance decreased with increasing frequency. The behavior reflected the ability of maximum amount of charge holding being at a 4.0 kHz. The analysis of the capacitance-voltage characteristics at fixed frequencies reflected a frequency dependent barrier height and acceptors density. The decrease in the barrier height and acceptors density with increasing frequency is mainly due to the inability of the free charge to follow the ac signal. (C) 2011 Elsevier B.V. All rights reserved.Article Citation - WoS: 2Geoengineering Properties of the Ertugrul (cayirkoy) District, Nilufer Province, Bursa-Turkey, by Using Geophysical Methods and Borehole Data(Elsevier, 2020) Cetin, Fatma; Kutluk, Hatice; Aydemir, AttilaIn this study, soil classification experiments and geophysical studies are carried out for the evaluation of local ground soil conditions by using the data and samples from the boreholes in the Quaternary sediments in the Ertugrul district of Nilufer, Bursa, then the engineering parameters and index classifications are also investigated with the soil mechanics experiments using the disturbed samples from the drill holes. The grade of swelling (bulking) potential in the ground soil is found medium, high and very high in different parts of the study area. The basement units for the constructions bear very low liquefaction risk. The plasticity index varies between 9 and 25, but active mass movements are not expected. However, engineering problems such as swelling (bulking), soil settlements, bearing capacity reduction may be expected under the seismic forces because of the alluvial composition, 0-5 degree soil inclinations and being located in the 1st degree earthquake hazard risk zone. Therefore, the study area may be classified in the 'precautionary zone' in the urbanization category in terms of engineering problems. (C) 2020 Elsevier B.V. All rights reserved.Article Citation - WoS: 10Citation - Scopus: 15Bifunctional Praseodymium-Doped Sns2 Thin Films for Photocatalytic and Antibacterial Applications(Elsevier, 2024) Ech-Chergui, Abdelkader Nebatti; Bennabi, Farid; Isik, Mehmet; Khane, Yasmina; Garcia, Francisco Jose Garcia; Kadari, Ali Sadek; Amrani, BouhalouaneThis paper introduces a novel application of bifunctional Pr-doped SnS2 thin films, demonstrating their efficacy in both photocatalytic degradation of dye and antibacterial activities. The thin films were fabricated using an eco-friendly spray-coated method, encompassing undoped and Pr-doped SnS2 variations. The study comprehensively examines the structural, morphological, chemical, photocatalytic, and antibacterial characteristics of these films. The crystal structure of both undoped and Pr-doped SnS2 thin films exhibited hexagonal patterns, prominently favouring the growth in (1 0 1) orientation. Notably, an increase in crystallite size was observed with higher levels of Pr-doping. Raman spectroscopy analysis highlighted a distinct peak at 315 cm -1, corresponding to the A1 g vibrational mode associated with Sn-S bonds along the c-axis of the structure. Employing X ray Photoelectron Spectroscopy (XPS), the presence of essential components - Sn, S, and Pr - within the fabricated thin films was confirmed, consistent with experimental values of undoped and Pr -doped SnS2-x compositions. Importantly, the XPS analysis confirmed the integration of the Pr3+ oxidation state within Pr -doped SnS2 films. The photocatalytic degradation and antibacterial activities of the films were investigated. Notably, the photocatalytic potential of the synthesized materials against Congo Red exhibited a direct correlation with the Pr3+ doping percentage, indicating enhanced pollutant degradation with increasing doping levels. Similarly, the antibacterial performance against Escherichia coli displayed improvement with increasing Pr -doping content, highlighting the promising antimicrobial capabilities of the films. This study presents an innovative avenue to address both organic pollutant degradation and microbial control. By harnessing the attributes of Pr -doped SnS2 thin films, this research introduces a promising strategy for sustainable material applications in environmental purification and improvement in public health.Article Citation - WoS: 4Citation - Scopus: 6An Automata Networks Based Preprocessing Technique for Artificial Neural Network Modelling of Primary Production Levels in Reservoirs(Elsevier, 2007) Kilic, Hurevren; Soyupak, Selcuk; Tuzun, Ilhami; Ince, Ozlem; Basaran, GokbenPrimary production in lakes and reservoirs develops as a result of complex reactions and interactions. Artificial neural networks (ANN) emerges as an approach in quantification of primary productivity in reservoirs. Almost all of the past ANN applications employed input data matrices whose vectors represent either water quality parameters or environmental characteristics. Most of the time, the components of input matrices are determined using expert opinion that implies possible factors that affect output vector. Major disadvantage of this approach is the possibility of ending-up with an input matrix that may have high correlations between some of its components. In this paper, an automata networks (AN) based preprocessing technique was developed to select suitable and appropriate constituents of input matrix to eliminate redundancy and to enhance calculation efficiency. The proposed technique specifically provides an apriori rough behavioral modeling through identification of minimal AN interaction topology. Predictive ANN models of primary production levels were developed for a reservoir following AN based pre-modeling step. The achieved levels of model precisions and performances were acceptable: the calculated root mean square error values (RMSE) were low; a correlation coefficient (R) as high as 0.83 was achieved with an ANN model of a specific structure. (c) 2006 Elsevier B.V. All rights reserved.Article Citation - WoS: 47Citation - Scopus: 44Investigation of Structural, Electronic, Magnetic and Lattice Dynamical Properties for Xcobi (x: Ti, Zr, Hf) Half-Heusler Compounds(Elsevier, 2020) Surucu, Gokhan; Isik, Mehmet; Candan, Abdullah; Wang, Xiaotian; Gullu, Hasan HuseyinStructural, electronic, magnetic, mechanical and lattice dynamical properties of XCoBi (X: Ti, Zr, Hf) Half-Heusler compounds have been investigated according to density functional theory and generalized gradient approximation. Among alpha, beta and gamma structural phases, gamma-phase structure has been found as the most stability characteristics depending on the calculated formation enthalpies, energy-volume dependencies and Cauchy pressures. Energy-volume plots of possible magnetic orders of gamma-phase XCoBi compounds have been analyzed and the most stable order has been found as paramagnetic nature. The theoretical studies on gamma-phase structures resulted in band gap energies of 0.96, 0.99 and 0.98 eV for TiCoBi, ZrCoBi and HfCoBi semiconducting compounds, respectively. Born-Huang criteria applied on elastic constants of interest compounds has indicated that gamma-phase is also mechanically stable for all studied compounds. In addition, various mechanical, lattice dynamical and thermodynamical parameters of XCoBi compounds have been calculated in the present study.
