Browsing by Author "Goksen, Kadir"

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Electronic and Optical Properties of Gas: a First-Principles Study
(Gazi Univ, 2010) Erdinc, Bahattin; Akkus, Harun; Goksen, Kadir
The electronic band structure and optical properties of hexagonal GaS are investigated using the density functional theory. The calculated band structure shows that the crystal has an indirect band gap with the value of 1.54 eV in the Brillouin zone at the Gamma -> M. The structural optimization has been performed using the generalized gradient approximation (GGA) and the local density approximation (LDA). The calculated structure optimization of GaS has been compared with the experimental results and has been found to be in good agreement with each other. Furthermore, the linear photon-energy-dependent dielectric functions and some optical constants such as energy-loss functions for volume and surface, extinction, reflectivity and absorption coefficients, refractive index and effective number of valence electrons per unit cell participating in the interband transitions have been calculated.
Metal/Semiconductor Contact Properties of Al/Co(ii)complex Compounds
(Elsevier, 2011) Temirci, Cabir; Gulcan, Mehmet; Goksen, Kadir; Sonmez, Mehmet
A ligand(N-APTH) and Co(II)complex compound of bidentate ligand which contains a ring of the pyrimidine have been produced. For the optical transmission measurements of the Co(II)complex compound thin films, a UV-Visible (UV-Vis) spectrophotometer was employed. As a result of optical measurements. it was revealed that Co(II)complex compound tends to show a semiconductor characteristic with the bandgap value of 3.46 eV. An attempt has been made to explore the rectifying and ohmic properties of Al/Co(II)complex compound/Cu structures assuming that Co(II)complex compound may exhibit a rectifier or ohmic behavior, depending on the fabrication process, when brought into an appropriate contact with a metal. From current-voltage (I-V) measurements, it was found that the device could show good ohmic and rectifying properties intentionally depending on the experimental process followed during fabrication. (C) 2010 Published by Elsevier B.V.
Ohmic and Rectifier Properties of Al/Ligand(n-apth) and Al/Cu(ii)complex Contacts
(Elsevier, 2010) Temirci, Cabir; Guelcan, Mehmet; Goksen, Kadir; Soenmez, Mehmet
We have produced a Ligand(N-APTH) and Cu(II)Complex of bidentate ligand containing a ring of the pyrimidine. Optical transmission measurements of the Ligand(N-APTH) and Cu(II)Complex thin films were performed by using a UV-Visible (UV-VIS) spectrophotometer. From the optical measurements, it was seen that the materials show semiconductor behaviors giving appropriate bandgaps with the values of 3.15 eV and 2.36 eV for Ligand(N-APTH) and Cu(II)Complex, respectively. With the pre-assumption that the material may exhibit a rectifier or ohmic behavior when it is brought into an appropriate contact with a metal, an attempt to explore the rectifying and ohmic properties of Al/Ligand(N-APTH)/Cu and All Cu(II)Complex/Cu contacts was made. As a result of current-voltage (I-V) measurements, it was discovered that the devices show excellent rectifier properties with a rectification ratio of about 10(-3) for All Ligand(N-APTH)/Cu and 10(-5) for Al/Cu(II)Complex/Cu rectifier contacts, respectively. (C) 2010 Elsevier B.V. All rights reserved.