Yazar "Kocyigit, S." seçeneğine göre listele

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    Electrical and dielectric properties of Au/1% graphene (GP)+Ca1.9Pr0.1Co4Ox doped poly(vinyl alcohol)/n-Si structures as function of temperature and voltage
    (Canadian Science Publishing, 2015) Cetinkaya, H. G.; Kaya, A.; Altindal, S.; Kocyigit, S.
    Electrical and dielectric properties of Au/1% graphene (GP)+Ca1.9Pr0.1Co4Ox doped poly(vinyl alcohol)/n-Si structures have been investigated using the admittance spectroscopy method in the temperature and voltage ranges of 160-300 K and -4-5 V, respectively. Experimental results show that both the main electrical and dielectric parameters, such as barrier height (Phi(b)), depletion layer width (W-d), series resistance (R-s) of structure, real and imaginary parts of dielectric constant (epsilon', epsilon '') and electric modulus (M' and M ''), tan delta, and AC conductivity (sigma(ac)) were found to be strong functions of temperature and applied bias voltage. M' and M '' versus V plots have a peak at about 1 V. While the peak position shifted towards negative biases, the magnitude of the peak decreases with increasing temperature. Such peak behavior in M' and M '' can be attributed to the existence of particular density distribution profile interface states at the interfacial layer-n-Si interface and their reordering and restructure under external electric field and interface polarization. These peaks also indicated that the Au/1% GP+Ca1.9Pr0.1Co4Ox doped poly(vinyl alcohol)/n-Si structure exhibits relaxation phenomena.
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    On double exponential forward bias current-voltage (I-V) characteristics of Au/Ca3Co4Ga0.001Ox/n-Si/Au (MIS) type structures in temperature range of 80-340 K
    (Taylor & Francis Ltd, 2015) Maril, E.; Altindal, S.; Kaya, A.; Kocyigit, S.; Uslu, I.
    Current transport mechanisms (CTMs) of Au/Ca3Co4Ga0.001Ox/n-Si/Au (MIS) type structures were investigated using current-voltage (I-V) characteristics in the temperature range of 80-340K. Semilogarithmic I-V plots show two linear regions corresponding to low (0.075-0.250V) and moderate (0.27-0.70V) biases, respectively. Zero-bias barrier height (phi(B0)) was observed to increase with increase in the temperature, whereas opposite behaviour was observed for ideality factor (n). phi(B0) and (n(-1)-1) vesus q/2kT and phi(B0) versus n plots were drawn to get an evidence of Gaussian distribution (GD) of the barrier heights. These plots, too, show two linear regions corresponding to low (80-160K) and high (200-340K) temperature ranges (LTR and HTR), respectively. Mean value of barrier height ( [GRAPHICS] (B0)) and standard deviation (sigma(s)) were extracted from the intercept and slope of phi(B0) versus q/2kT plots for two linear regions as 0.382eV, 0.0060V for LTR and 0.850eV, 0.135V for HTR at low biases and 0.364eV, 0.0059V for LTR and 0.806eV, 0.132V for HTR at high biases, respectively. [GRAPHICS] (B0) and Richardson constant (A*) values were also obtained from the intercept and slope of the modified Richardson (Ln(I-o/T-2)-(q(2)sigma(2)(s)/2k(2)T(2)) versus q/kT) plots as 131.81 Acm(-2)K(-2), 0.381eV for LTR and 129.35 Acm(-2)K(-2), 0. 854eV for HTR at low biases and 148.01 Acm(-2)K(-2), 0.377eV for LTR and 143.77 Acm(-2)K(-2), 0.812eV for HTR at high biases, respectively. In conclusion, CTM in the structure can be successfully explained in terms of thermionic emission theory with the double GD of barrier heights.
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    On the analysis of the leakage current in Au/Ca3Co4Ga0.001Ox/n-Si structure in the temperature range of 80-340 K
    (Elsevier Sci Ltd, 2015) Maril, E.; Kaya, A.; Kocyigit, S.; Altindal, S.
    The temperature dependent reverse bias leakage current-voltage (I-r-V-r) of the Au/Ca3Co4Ga0.001Ox/n-Si structure has been investigated in the temperature range of 80-340 K. The Ln(J(r)/E-r) vs E-0.5 plots show straight lines with different slopes in the intermediate reverse bias voltages for each temperature. Both the intercepts B(T) and slopes m(T) values were obtained from these plots for each temperature. Their values vs q/kT plots were drawn and they show a linear behavior except for two low temperatures (80 and 120 K). The dielectric constant (epsilon(s)) of interfacial Ca3Co4Ga0.001Ox. layer and the barrier height (phi(t)) which is necessary electron emission from the trap values were found from the slope of these plots, respectively. Experimental results show that the I-r-V-r, characteristics can be well described by the electric field dependence so the dominant conduction mechanisms are either Frenkel-Poole emission (FPE) or Schottky emission (SE) in this structure. The es and phi(t) values were found as 3.1 and 37.1 meV, respectively. It is clear that the value of phi(t) is considerably low and the value of dielectric constant (3.1) is closed to the dielectric value conventional of SiO2 insulator layer. These results confirmed that the (Ca3Co4Ga0.001Ox) interfacial layer can be used instead of a conventional of SiO2 insulator layer in the terms of flexibility, easy production and low cost. (C) 2014 Elsevier Ltd. All rights reserved.
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    On the temperature dependent forward bias current-voltage (I-V) characteristics in Au/2% graphene-cobalt doped (Ca3Co4Ga0.001Ox)/n-Si structure
    (Elsevier Sci Ltd, 2015) Maril, E.; Kaya, A.; Cetinkaya, H. G.; Kocyigit, S.; Altindal, S.
    In order to good interpret of temperature dependent main electrical parameters in Au/2% graphene-cobalt (GC) doped (Ca3Co4Ga0.001Ox)/n-Si structure, forward bias current-voltage (I-V) characteristics have been investigated in the temperature range of 80340 K. The possible current-conduction mechanisms (CCMs) in this structure was also investigate in detail. The ideality factor (n), reverse saturation current (I-o), and zero-bias barrier height (Phi(Bo)) values were found as 14.5, 7.2 x 10(-6) A, 0.141 eV at 80K and 3.18, 1.7 x 10(-3) A, and 0.526 eV at 340 K, respectively. It is clear that both the value of n and Phi(Bo) are strong function of temperature. While the value of n decreases with increasing temperature, Phi(Bo) increases. In order to explain such behavior of BH the Phi(Bo) and n, Phi(Bo) vs q/2kT, Phi(Bo) vs n, and (n(-1)-1) vs q/2kT plots were drawn to obtain an evidence of a Gaussian distribution (GD) of the BHs and it shows a straight line. The mean value of BH ((Phi) over bar (Bo)) and standard deviation (sigma(s)) were found from the slope and intercept of this plot as 0.614 eV and 0.088 V, respectively. By using the modified Richardson plot, the (Phi) over bar (Bo) and Richardson constant (A*) values were obtained from the slope and intercept of this plot as 0.604 eV and 108.23 A cm(-2) K-2, respectively. It is clear that this value of A* ( = 108.23 A cm(-2) K-2) is very close to the theoretical value 112 A cm(-2) K-2 for n-Si. In conclusion, the temperature dependence of the forward bias I-V characteristics of the structure can be successfully explained on the basis of a thermionic emission (TE) mechanism with GD of the BHs. (C) 2015 Elsevier Ltd. All rights reserved.