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    Current-transport mechanism in Au/V-doped PVC plus TCNQ/p-Si structures
    (World Scientific Publ Co Pte Ltd, 2015) Tecimer, H.; Vural, O.; Kaya, A.; Altindal, S.
    The forward and reverse bias current-voltage (I-V) characteristics of Au/V-doped polyvinyl chloride+Tetracyanoquino dimethane/porous silicon (PVC+TCNQ/p-Si) structures have been investigated in the temperature range of 160-340 K. The zero bias or apparent barrier height (BH) (Phi(ap) = Phi(Bo)) and ideality factor (n(ap) = n) were found strongly temperature dependent and the value of nap decreases, while the n(ap) increases with the increasing temperature. Also, the Phi(ap) versus T plot shows almost a straight line which has positive temperature coefficient and it is not in agreement with the negative temperature coefficient of ideal diode or forbidden bandgap of Si (alpha(Si) = -4.73x10(-4) eV/K). The high value of n cannot be explained only with respect to interfacial insulator layer and interface traps. In order to explain such behavior of Phi(ap) and nap with temperature, Phi(ap) Versus q/2kT plot was drawn and the mean value of ((Phi) over bar (Bo)) and standard deviation (sigma(s)) values found from the slope and intercept of this plot as 1.176 eV and 0.152 V, respectively. Thus, the modified (ln(I-o/T-2) - (q sigma(s))(2)/2(kT)(2) versus (q/kT) plot gives the (Phi) over bar (Bo) and effective Richardson constant A* as 1.115 eV and 31.94 A.(cm.K)(-2), respectively. This value of A* (= 31.94 A.(cm.K)(-2)) is very close to the theoretical value of 32 A.(cm.K)(-2) for p-Si. Therefore, the forward bias I-V-T characteristics confirmed that the current-transport mechanism (CTM) in Au/V-doped PVC+TCNQ/p-Si structures can be successfully explained in terms of the thermionic emission (TE) mechanism with a Gaussian distribution (GD) of BHs at around mean BH.
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    Frequency and voltage dependence of dielectric properties and electric modulus in Au/PVC + TCNQ/p-Si structure at room temperature
    (Elsevier, 2014) Kaya, A.; Vural, O.; Tecimer, H.; Demirezen, S.; Altindal, S.
    Au/PVC + TCNQ/p-Si structure was fabricated and real and imaginary parts of the dielectric constant (epsilon', epsilon ''), loss tangent (tan delta), and the real and imaginary parts of the electric modulus (M', M '') and ac conductivity (sigma(ac)) of this structure have been investigated in wide frequency a range of 1 kHz-5 MHz at room temperature. All of these parameters were found strong function of frequency and voltage especially in the inversion and depletion regions at low frequencies due to interfacial polarization and charges at interface states (N-ss). The decrease in epsilon' and epsilon '' with increasing frequency indicated that the interfacial dipoles have less time to orient themselves in the direction of the alternate field. While the value of M' increase with increasing frequency and reach a maximum, M '' shows a peak and the peak position shifts to higher frequency with increasing applied voltage. The ln(sigma(ac)) vs ln(omega) plot of the structure for 0.5 V has three linear regions (I, II and III) with different slopes which correspond to low, intermediate and high frequency ranges, respectively. Such behavior of ln(sigma(ac)) vs ln(omega) plot indicated that there are three different conduction mechanisms in the Au/PVC + TCNQ/p-Si structure at room temperature. (C) 2013 Elsevier B. V. All rights reserved.
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    The effect of Mo-doped PVC plus TCNQ interfacial layer on the electrical properties of Au/PVC plus TCNQ/p-Si structures at room temperature
    (Elsevier Sci Ltd, 2015) Demirezen, S.; Kaya, A.; Vural, O.; Altindal, S.
    The effect of Mo-doped and undoped PVC+TCNQ interfacial layer on electrical characteristics of a Au/PVC+TCNQ/p-Si structure was investigated using current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements at room temperature. The energy dependent interface states density (N-ss) was obtained from the forward bias I-V data by taking into account voltage dependent effective barrier height (Phi(e)) for two diodes,. i.e. with and without Mo doping. The voltage dependent resistance (R-i) of structures was also obtained using Ohm's law and the method of Nicollian and Brews for the diodes. In order to eliminate the effect of series resistance (R-s), C and G/omega at high frequency values were corrected. N-ss and R-s values were compared between the diodes and experimental results showed that N-ss and R-s values of the Mo-doped PVC+TCNQ structure are considerably lower than those of the undoped PVC+TCNQ structure. The other important parameters such as ideality factor (n), reverse saturation current (I-s), zero-bias barrier heights (Phi(B0)) and R-s were obtained from forward bias I-V data by using I-V, Cheung and Norde methods. Experimental results confirmed that the Mo-doped (PVC+TCNQ) layer considerably improved the performance of the Au/PVC+TCNQ/p-Si structure. (C) 2015 Elsevier Ltd. All rights reserved.