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Article Citation - WoS: 1Citation - Scopus: 1Structural and Optical Properties of Thermally Evaporated Ga-In Thin Films(World Scientific Publ Co Pte Ltd, 2014) Isik, Mehmet; Gullu, Hasan HuseyinIn this paper, structural and optical properties of Ga-In-Se (GIS) thin films deposited by thermal evaporation technique have been investigated. The effect of annealing was also studied for samples annealed at temperatures between 300 degrees C and 500 degrees C. X-ray diffraction, energy dispersive X-ray analysis and scanning electron microscopy have been used for structural characterization. It was reported that increase of annealing temperature results with better crystallization and chemical composition of the films were almost same. Optical properties of the films were studied by transmission measurements in the wavelength range of 320-1100 nm. The direct bandgap transitions with energies in the range of 1.52 eV and 1.65 eV were revealed for the investigated GIS films. Photon energy dependence of absorption coefficient showed that there exist three distinct transition regions for films annealed at 400 degrees C and 500 degrees C. The quasicubic model was applied for these transitions to calculate crystal-field splitting and spin-orbit splitting energy values.Article A Density Functional Theory Study on the Structural and Electronic Properties of Pbx< (x Plus y Plus z=2, 3) Clusters(World Scientific Publ Co Pte Ltd, 2018) Pekoz, Rengin; Erkoc, SakirThe structural and electronic properties of neutral ternary PbxSbySez clusters (x y + z = 2, 3) in their ground states have been explored by means of density functional theory calculations. The geometric structures and binding energies are systematically explored and for the most stable configurations of each cluster type vibrational frequencies, charges on atoms, energy difference between highest occupied and lowest unoccupied molecular orbitals, and the possible dissociations channels have been analyzed. Depending on being binary or ternary cluster and composition, the most energetic structures have singlet, doublet or triplet ground states, and trimers prefer to form isosceles, equilateral or scalene triangle structure.Article Citation - WoS: 2Predicting Financial Failure of the Turkish Banks(World Scientific Publ Co Pte Ltd, 2006) Doganay, M. Mete; Ceylan, Nildag Basak; Aktas, RamazanBanks are the most important financial institutions in Turkey because other financial institutions are not developed efficiently yet. Turkish banks experienced financial difficulties and a substantial amount of banks failed in the past. This event urged the government to initiate measures to prevent banks from getting into financial difficulties. As a result of these measures, Turkish banking system currently seems to be very attractive for the foreign investors willing to invest in this sector. One of the main concerns of the foreign investors is a possibility of a new banking crisis although it is very remote at this time. The purpose of this study is to develop early warning systems predicting the financial failure at least three years ahead of financial date. A number of multivariate statistical models such as multiple regression, discriminant analysis, logit, probit are used. We found that the most appropriate model is logit. The significant variables obtained from the models explain very well the causes of the bank failures. Our models can be used to assist interested parties to predict the probability of financial failure of Turkish banks.Review Citation - WoS: 8Citation - Scopus: 10Group 12 Elements and Their Small Clusters: Electric Dipole Polarizability of Zn, Cd and Hg, Zn2 Dimer and Higher Znn< Microclusters and Neutral, Cationic and Anionic Zinc Oxide Molecules (zno, Zno+ and Zno-)(World Scientific Publ Co Pte Ltd, 2012) Oymak, Huseyin; Erkoc, SakirThis review is in general about group 12 elements and their small microclusters. In this part, after presenting an extensive literature survey of the electric dipole polarizability studies of the Zn, Cd and Hg atoms, we specifically target zinc-containing small clusters, beginning with the Zn-2 dimer, the Zn-3 trimer, higher Zn-n clusters and the neutral, cationic and anionic zinc oxide clusters: ZnO, ZnO+ and ZnO-. We tabulated experimental and theoretical results for the spectroscopic constants (dissociation energy D-e or D-0, bond length r(e), fundamental frequency w(e), anharmonicity constant w(e)x(e) and dipole moment mu(e)) of the diatomic clusters and the first and second ionization potentials IP1 and IP2 and electron affinity EA of the species reviewed.Article Citation - WoS: 4Citation - Scopus: 4Optical Characterization of Ga2ses Layered Crystals by Transmission, Reflection and Ellipsometry(World Scientific Publ Co Pte Ltd, 2015) Isik, Mehmet; Gasanly, NizamiOptical properties of Ga2SeS crystals grown by Bridgman method were investigated by transmission, reflection and ellipsometry measurements. Analysis of the transmission and reflection measurements performed in the wavelength range of 400-1100 nm at room temperature indicated the presence of indirect and direct transitions with 2.28 eV and 2.38 eV band gap energies. Ellipsometry measurements were carried out in the 1.2-6.0 eV spectral region to get information about optical constants, real and imaginary parts of the pseudodielectric function. Moreover, the critical point (CP) analysis of the second derivative spectra of the pseudodielectric constant in the above band gap region was accomplished. The analysis revealed the presence of five CPs with energies of 3.87, 4.16, 4.41, 4.67 and 5.34 eV.
