Yazar "Altindal, Semsettin" seçeneğine göre listele

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    Capacitance/Conductance-Voltage-Frequency Characteristics of Au/PVC+TCNQ/p-Si Structures in Wide Frequency Range
    (Ieee-Inst Electrical Electronics Engineers Inc, 2014) Kaya, Ahmet; Tecimer, Huseyin; Vural, Ozkan; Tasdemir, Ibrahim Hudai; Altindal, Semsettin
    The energy dependence of the interface states (N-ss) and relaxation time (tau) and capture cross section (sigma(p)) of N-ss in (Au/PVC+TCNQ/p-Si) heterojunction were investigated using high-low frequency capacitance (C-HF-C-LF) and conductance method, which contains many capacitance/conductance [C/(G/omega)-V] plots. The C value of the heterojunction increases with decreasing frequency as almost exponentially due to the existence of N-ss between metal and semiconductor. The N-ss and tau values have been obtained in the (0.053-E-v)-(0.785-E-v)-eV energy range by considering the voltage-dependent surface potential obtained from the lowest measurable frequency C-V curve at 1 kHz. The magnitude of N-ss ranges from 3.88x10(12) eV(-1)cm(-2) to 3.24 x 10(12) eV(-1)cm(-2). In the same energy range, the value of tau ranges from 5.73x10(-5) to 1.58x10(-4) s and shows almost an exponential increase with increasing bias from the top of the valance band edge toward the midgap of semiconductor. The obtained N-ss values from C-HF-C-LF and conductance methods are in good agreement with each other for the heterojunction. As a result, the mean value of N-ss was found on the order of 10(12) eV(-1)cm(-2) and this value is very suitable for an electronic device.
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    Electrical and dielectric properties and intersection behavior of G/?-V plots for Al/Co-PVA/p-Si (MPS) structures at temperatures below room temperature
    (Korean Physical Soc, 2014) Yucedag, Ibrahim; Kaya, Ahmet; Altindal, Semsettin; Uslu, Ibrahim
    Both the electrical and the dielectric properties of the Al/Co-doped polyvinyl alcohol/p-Si metal-polymer-semiconductor (MPS) structure have been studied using temperature-dependent admittance-voltage (C/G-V) measurements at temperatures below room temperature at 300 kHz. The C-V plot indicates two peaks for each temperature corresponding to inversion and accumulation regions, respectively. The first peak was attributed to a particular distribution of interface traps (D (it) ), and the second was attributed to the series resistance (R (s) ) and interfacial polymer layer. G/omega-V plots show almost U-shape behavior for all temperatures and a crossing at almost 3 V. Such behavior of the G/omega-V plots may be attributed to the lack of free charge at low temperatures. After this intersection point, while the value of the capacitance (C) starts decreasing, the G/omega continues to increase. The temperature-dependent real and imaginary parts of the dielectric constant (epsilon', epsilon aEuro(3)) and of the electric modulus (M', MaEuro(3)), as well as the ac electrical conductivity (sigma (ac) ), of structure were obtained using C and G data before and after the intersection point (at 2 and 6 V), respectively. Experimental results show that the epsilon', epsilon aEuro(3), loss tangent (tan delta), sigma (ac) , M', and MaEuro(3) values were strong functions of the temperature and the applied bias voltage. In addition, G/omega-T and epsilon aEuro(3)-T plots show two different behaviors, one before and the other after the intersection point.
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    Frequency and voltage-dependent electrical and dielectric properties of Al/Co-doped PVA/p-Si structures at room temperature
    (Iop Publishing Ltd, 2014) Yucedag, Ibrahim; Kaya, Ahmet; Altindal, Semsettin; Uslu, Ibrahim
    In order to investigate of cobalt-doped interfacial polyvinyl alcohol (PVA) layer and interface trap (D-it) effects, Al/pSi Schottky barrier diodes (SBDs) are fabricated, and their electrical and dielectric properties are investigated at room temperature. The forward and reverse admittance measurements are carried out in the frequency and voltage ranges of 30 kHz-300 kHz and -5 V-6 V, respectively. C-V or epsilon '-V plots exhibit two distinct peaks corresponding to inversion and accumulation regions. The first peak is attributed to the existence of Dit, the other to the series resistance (R-s), and interfacial layer. Both the real and imaginary parts of dielectric constant (epsilon ' and epsilon '') and electric modulus (M ' and M ''), loss tangent (tan delta), and AC electrical conductivity (sigma(ac)) are investigated, each as a function of frequency and applied bias voltage. Each of the M ' versus V and M '' versus V plots shows a peak and the magnitude of peak increases with the increasing of frequency. Especially due to the Dit and interfacial PVA layer, both capacitance (C) and conductance (G/w) values are strongly affected, which consequently contributes to deviation from both the electrical and dielectric properties of Al/Co-doped PVA/p-Si (MPS) type SBD. In addition, the voltage-dependent profile of Dit is obtained from the low-high frequency capacitance (CLF-CHF) method.