Yazar "Yildirim, M." seçeneğine göre listele

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    Capacitance and Conductance-Frequency Characteristics of Au/n-Si Schottky Structure with Perylene-Diimide (PDI) Organic Interlayer
    (SPRINGER, 2017) Yuksel, O. F.; Kus, M.; Yildirim, M.
    We report the interface properties of a perylene-diimide thin film between Au and n-Si substrate fabricated by the spin coating method. The relaxation time (tau) and interface trap density (D (it)) characteristics of the fabricated structure were obtained across various voltage ranges (0.0 V-300 mV) and various frequency ranges (1 kHz-1 MHz). We observed a peak in G (it)/omega versus log (f) plots from 0.0 V to 300 mV. This peak shows the presence of the interface state and its relaxation time. We observed a decrease in values at the same time as an increase in N (ss) values with the increasing applied voltage for the sample. The N (ss) and tau values found to be in the ranges 1.50 x 10(12) eV(-1) cm(-2)-2.83 x 10(12) eV(-1) cm(-2) and 2.83 x 10(-6) s-4.82 x 10(-7) s between 0.0 V and 0.3 V, respectively.
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    Electrical Characterization of Au/Fluorene-Carbazole (FC)/p-Si Schottky Barrier Diodes
    (ELSEVIER SCIENCE BV, 2016) Yildirim, M.; Tugluoglu, N.; Yuksel, O. F.; Erdogan, A.; Kus, M.
    The Fluorene-Carbazole (FC) was synthesized by Suziki method in this study. The organic semiconductor is prepared on p-type Si substrate by spin coating method. We have produced Au/FC/p-Si Schottky diodes. We have investigated the current-voltage characteristics over temperature range between 200 and 350 K. The measured current-voltage (I-V) characteristics of device have demonstrated a good rectification behaviour at all temperatures. The parameters such as the ideality factor (n), barrier height (Phi(B)) and series resistance (R-S) were determined from the experimental data using standard current-voltage analysis method. At T=200 K, we have found the values of the n and Phi(B) as 2.78 and 0.491 eV respectively. On the other hand, their values were found as n=1.86 and Phi(B)=0.779 eV at T=350 K. The values of R-S are calculated using Cheung and Cheung functions between 200 K and 350 K. The H(I)-I plot of Cheung and Cheung method shows RS of 1823.23 Omega for 200 K and value of 952.6 Omega for 350 K. (C) 2015 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of Conference Committee Members of International Semiconductor Science and Technology Conference 2015 (ISSTC 2015).
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    Optical characterization of Cu2ZnSnSe4-xSx nanocrystals thin film
    (ELSEVIER SCIENCE SA, 2016) Yildirim, M.; Ozel, F.; Tugluoglu, N.; Yuksel, O. F.; Kus, M.
    Cu2ZnSnSe4-xSx (CZTSeS) nanocrystals have been shown to be a potential application for sustainable thin-film solar cell devices. In this paper, we have presented the growth of nanocrystals CZTSeS and their thin films applications successfully prepared on soda-lime glass substrates by using spin coating techniques. The CZTSeS nanocrystals have been synthesized by hot-injection method. In-depth characterization has indicated that pure stoichiometric CZTSeS nanocrystals with an average particle size mostly distributed between 15 and 20 nm have been formed. We have analyzed the optical transmission and reflection spectra of nanocrystal CZTSeS thin film. Optical band gap E-g and absorption coefficient (a) of thin film have been determined by standard optical analysis and also several optical parameters such as refractive index (n), extinction coefficient (k), the Urbach energy (E-U) and real and imaginary parts of dielectric constant (epsilon) have been calculated. Detailed characterization data including X-ray diffraction, surface morphology, cross section analysis, optical transmittance and reflectance spectroscopy have been presented in order to use in the performance of single-junction solar devices. Optical measurements have showed a band gap of 1.51 eV, which is optimal for a single-junction solar device. (C) 2016 Elsevier B.V. All rights reserved.
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    The rate of Cu doped TiO2 interlayer effects on the electrical characteristics of Al/Cu:TiO2/n-Si (MOS) capacitors depend on frequency and voltage
    (PERGAMON-ELSEVIER SCIENCE LTD, 2020) Erdal, M. O.; Kocyigit, A.; Yildirim, M.
    In order to determine the surface states (N-ss), series resistance (R-s), and (Cu:TiO2) interlayer effects on the electrical characteristics of the Al/Cu:TiO2/n-Si metal oxide semiconductor (MOS) capacitors, both capacitance (C) and conductance (G) values were measured for frequency ranges of 10 kHz-1 MHz and +/- 5 V voltage ranges. In addition, to know Cu doping concentration effect on the MOS capacitor, the Al/Cu:TiO2/n-Si was fabricated with various rates Cu:TiO2 interlayer (5, 10, 15%) grown on n-Si susbtrate by spin-coating. The increase in capacitance via decreasing frequencies was attributed to the existence of N-ss and their relaxation time. The frequency dependent diffusion potential (V-d), doping of donor atoms (N-d), Fermi energy (E-F), barrier height (Phi b) and depletion layer width (W-d) values were extracted from the linear part of reverse bias C-2-V curves. While the value the R-s decreased with increasing frequency, the N-ss values increased for the three MOS capacitors. The profiles of N-ss and R-s depending on voltage were also plotted by Nicollian-Brews methods and using high-low frequency (C-HF-C-LF) capacitance, respectively. The mean values of N-ss for three capacitors were found at about 10(12) eV(-1)cm(-2) as suitable electronic devices. The lower values of the N-ss can be attributed to passivation effect of Cu:TiO2 interlayer.
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    Temperature dependence of current-voltage characteristics of Al/rubrene/n-GaAs (100) Schottky barrier diodes
    (ELSEVIER SCIENCE BV, 2016) Yuksel, O. F.; Tugluoglu, N.; Caliskan, F.; Yildirim, M.
    5,6,11,12-tetraphenylnaphthacene (rubrene) is fabricated by spin coating technique on n type GaAs (100) substrate. The current-voltage (I-V) characteristics of Al/rubrene/n-GaAs (100) Schottky diode have been measured in the temperature range of 100-300 K. The experimental values of saturation current (I-0), ideality factor (n) and barrier height (Phi(B)) are calculated as 2.749 pA, 6.051 and 0.297 eV at 100 K and 57.54 pA, 1.918 and 0.870 eV at 300 K, respectively. The values of series resistance (R-S) are calculated using Cheung functions at all temperatures. The R-S values are found as 1276.4 Omega and 119.7 Omega for 100 K and 300 K, respectively. It is found that barrier heights increased while ideality factors and series resistances decrease with the increasing temperature. (C) 2015 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of Conference Committee Members of International Semiconductor Science and Technology Conference 2015 (ISSTC 2015).