Yazar "Yuksel, Omer Faruk" seçeneğine göre listele

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    Double barrier heights in 5,6,11,12-tetraphenylnaphthacene (rubrene) based organic Schottky diode
    (ELSEVIER SCIENCE SA, 2013) Baris, Behzad; Yuksel, Omer Faruk; Tugluoglu, Nihat; Karadeniz, Serdar
    5,6,11,12-Tetraphenylnaphthacene (rubrene) was grown on p type Si (100) substrate using spin coating technique. We have fabricated an Al/rubrene/p-Si Schottky device and measured the current-voltage (I-V) characteristics in the temperature range from 75 to 300 K by steps of 25 K. An abnormal decrease in the experimental barrier height Phi(B) and an increase in the ideality factor n with a decrease in temperature have been observed. The I-V characteristics of Al/rubrene/p-Si Schottky diode are analyzed on the basis of thermionic emission (TE) theory and the assumption of double Gaussian distribution of barrier heights due to barrier inhomogeneities. The modified Richardson plots of In(I-0/T-2) - (1/2)(q sigma((i))(s0)/kT)(2) versus 1000/T gives [GRAPHICS] and A(R)((i)) values as 1.186 and 0.571 eV, and 33.85 and 84.63 A cm(-2) K-2, respectively. The modified Richardson constant value of A(R)((2)) = 33.85 A cm(-2) K-2 for high temperature range (175-300 K) is very close to the theoretical value of 32 A cm(-2) K-2 for p-Si. (c) 2013 Elsevier B.V. All rights reserved.
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    Improvement of diode parameters in Al/n-Si Schottky diodes with Coronene interlayer using variation of the illumination intensity
    (ELSEVIER SCIENCE BV, 2017) Pakma, Osman; Cavdar, Sukru; Koralay, Haluk; Tugluoglu, Nihat; Yuksel, Omer Faruk
    In present work, Coronene thin films on Si wafer have been deposited by the spin coating method. It has been ultimately produced Al/Coronene/n-Si/In Schottky diode. Current-voltage (I-V) measurements have been used to determine the effect of illumination intensity in the Schottky diodes. The barrier height (FB) values increased as ideality factor (n) values decreased with a increase in illumination intensity. The FB values have been found to be 0.697 and 0.755 eV at dark and 100 mW/cm(2), respectively. The n values have been found to be 2.81 and 2.07 at dark and 100 mW/cm(2), respectively. Additionally, the series resistance (R-s) values from modified Norde method and interface state density (N-ss) values using current-voltage measurements have been determined. The values of R-s have been found to be 1924 and 5094 Omega at dark and 100 mW/cm(2), respectively. The values of N-ss have been found to be 4.76 x 10(12) and 3.15 x 10(12) eV(-1) cm(-2) at dark and 100 mW/cm(2), respectively. The diode parameters are improved by applying the variation of illumination intensity to the formed Schottky diodes.
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    Investigation of optical band gap and device parameters of rubrene thin film prepared using spin coating technique
    (ELSEVIER SCIENCE SA, 2014) Tugluoglu, Nihat; Baris, Behzad; Gurel, Hatice; Karadeniz, Serdar; Yuksel, Omer Faruk
    Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200-700 nm. The results of the absorption coefficient (alpha) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV-vis region shows two peaks at 250 nm and 300 nm. The analysis of the spectral behavior of the absorption coefficient (alpha) in the absorption region revealed indirect allowed transition with corresponding energy 2.31 eV. The value of Urbach energy (E-U) was determined to be 1.169 eV. The current-voltage (I-V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I-V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions. (c) 2013 Elsevier B.V. All rights reserved.
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    Optical dispersion and dielectric properties of rubrene organic semiconductor thin film
    (SPRINGER, 2014) Baris, Behzad; Ozdemir, Hatice Gurel; Tugluoglu, Nihat; Karadeniz, Serdar; Yuksel, Omer Faruk; Kisnisci, Zeynep
    Rubrene thin film has been fabricated on a glass substrate by spin-coating at 300 K. The optical dispersion and dielectric properties of the film have been determined from the analysis of transmittance and reflectance measurements at normal incident of light between 200 and 700 nm. The optical transmittance of the film was estimated as of 80-85 % in the visible range. Optical absorption characteristics show that the absorption mechanism is due to the indirect transition. The transport and onset optical energy gaps were determined as 2.93 and 2.31 eV, respectively. Single term Sellmeier dispersion relation and Wemple-DiDomenico single oscillator model were used to determine the optical dispersion parameters. Several dispersion parameters such as lattice dielectric constant, optical dielectric constant at higher frequency, dispersion energy, oscillator energy, the ratio of carrier concentration to the effective mass, the average oscillator wavelength, and average oscillator strength were determined by analysis of refractive index dispersion. The loss factor, the electric modulus, the optical conductivity, the volume and surface energy loss functions, and the relaxation time were also evaluated from the optical dielectric constants analysis.