Yazar "Tunç, Tuncay" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    The Au/polyvinyl alcohol (Co, Zn-doped)/n-type silicon Schottky barrier devices
    (ELSEVIER SCIENCE SA, 2011) Dökme, İlbilge; Tunç, Tuncay; Uslu, İbrahim; Altındal, Şemsettin
    Metal/polyvinyl alcohol/n-type silicon Schottky barrier (SB) devices have been fabricated in this study. The importance of this study is that PVA (Co, Zn doped) nanofiber film as an interfacial layer was formed by the electrospinning technique on n-type silicon substrate. The forward and reverse bias current-voltage (I-V) characteristics of this device were measured at room temperature. The Phi(Bo) value of about 0.749 eV obtained from I-V characteristics indicates that the contact potential barrier exists at the interface between organic and inorganic semiconductor layer, that is, PVA/n-Si interface. The variation in the capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics of the Au/PVA (Co. Zn doped)/n-Si SB devices have been systematically investigated as a function of frequencies in the frequency range of 2 kHz-2 MHz at room temperature. The effects of density of interface states (N-ss) and series resistance (R-s) on I-V, C-V and G/omega-V characteristics were investigated. The high-frequency capacitance (C-m) and conductance (G(m)/omega) values measured under reverse bias were corrected to decrease the effects of series resistance. These results show that the locations of interface states between Si/PVA and series resistance have a significant effect on electrical characteristics of the Au/PVA (Co, Zn doped)/n-Si SB devices. (C) 2011 Elsevier B.V. All rights reserved.
  • Küçük Resim
    Öğe
    Frequency and Temperature Dependence of Dielectric Properties of Au/Polyvinyl Alcohol (Co, Ni-doped)/n-Si Schottky Diodes
    (Taylor & Francis As, 2010) Tunç, Tuncay; Uslu, İbrahim; Dökme, İlbilge; Altındal, Şemsettin; Uslu, Habibe
    The dielectric properties and AC conductivity of Au/polyvinyl alcohol (Co, Ni-doped)/n-Si Schottky diodes (SDs) were investigated in the frequency range 1kHz-1MHz and in the temperature range 80-400K. The frequency and temperature dependence of dielectric constant (epsilon'), dielectric loss (epsilon''), loss tangent (tan ), AC electrical conductivity (sigma ac) and the real and imaginary parts of the electric modulus (M' and M'') were found to be a strong function of frequency and temperature. The values of epsilon', epsilon'' and tan decrease with increasing frequency, while they increase with increasing temperature, especially above 275K. The values of sigma ac increase with both increasing frequency and temperature. Such temperature-related behavior of sigma ac can be attributed to the high mobility of free charges at high temperature. Electric modulus formalism was also analyzed to obtain experimental dielectric data. The values of M' and M'' increase with increasing frequency, while they decrease with increasing temperature. The interfacial polarization, which more easily occurs at low frequencies and high temperatures, consequently contributes to the improvement of the dielectric properties of SDs.
  • Küçük Resim Yok
    Öğe
    The Illumination Intensity and Applied Bias Voltage on Dielectric Properties of Au/Polyvinyl Alcohol (Co, Zn-Doped)/n-Si Schottky Barrier Diodes
    (WILEY-BLACKWELL, 2011) Uslu, Habibe; Altındal, Şemsettin; Tunç, Tuncay; Uslu, Ibrahim; Mammadov, Tofig S.
    The Au/polyvinyl alcohol (PVA) (Co, Zndoped)/ n-Si Schottky barrier diodes (SBDs) were exposed to various illumination intensities. Illumination effect on the dielectric properties has been investigated by using capacitance- voltage (C-V) and conductance-voltage (G/omega-V) characteristics at 1 MHz and room temperature. The values of dielectric constant (epsilon'), dielectric loss (epsilon ''), loss tangent (tan delta), electric modulus (M' and M ''), and AC electrical conductivity (sigma(AC)) were found strongly intensity dependent on both the illumination levels and applied bias voltage especially in depletion and accumulation regions. Such bias and illumination dependency of these parameters can be explained on the basis of Maxwell-Wagner interfacial polarization and restructuring and reordering of charges at interface states. In addition, the epsilon'-V plots also show an intersection feature at similar to 2.8 V and such behavior of the epsilon'-V plots appears as an abnormality compared with the conventional behavior of an ideal SBD. The obtained results revealed that illumination intensity enhances the conductivity of Au/PVA(Co, Zndoped)/ n-Si SBD. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 322-328, 2011
  • Küçük Resim
    Öğe
    Preparation of Gadolina Stabilized Bismuth Oxide Doped with Boron via Electrospinning Technique
    (SPRINGER, 2012) Tunç, Tuncay; Uslu, İbrahim; Durmuşoğlu, Şenol; Keskin, Selda; Aytimur, Arda; Akdemir, Ahmet
    In this study, boron doped and undoped poly (vinyl) alcohol/bismuth-gadolina acetate (PVA/Bi-Gd) nanofibers were prepared using electrospinning technique then calcinated at 800 degrees C for 2 h. The originality of this study is the addition of boron to metal acetates. The effects of boron doping were investigated in terms of solution properties, morphological changes and thermal characteristics. The characteristics of the fibers were investigated with FT-IR, XRD, SEM and BET. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats were 204 and 123 nm, respectively. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 140 and 118 nm, respectively. The BET results showed that boron undoped and doped Bi2O3-La2O3 nanocrystalline powder ceramic structures sintered at 800 degrees C have surface areas of 59.72 and 39.80 m(2)/g, respectively.