Yazar "Uslu, Ibrahim" seçeneğine göre listele
Listeleniyor 1 - 4 / 4
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe 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, IbrahimBoth 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.Öğe Electronic transport of Au/(Ca1.9Pr0.1Co4Ox)/n-Si structures analysed over a wide temperature range(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2015) Alialy, Sahar; Kaya, Ahmet; Marıl, Elif; Altındal, Şemsettin; Uslu, IbrahimThe barrier height (BH) of the Au/(Ca1.9Pr0.1Co4Ox)/n-Si structure was evaluated in the temperature range of 120-360 K using current-voltage (I-V) measurements. The zero-bias BH (?Bo) and ideality factor (n) values deduced from standard thermionic emission theory were found to be 0.35 eV and 6.30 at 120 K and 0.83 eV and 5.1 at 360 K, respectively. Because such changes in ?Bo were not in agreement with the negative temperature coefficient (?) of the Si band gap, effects of tunnelling and BH inhomogeneity were added to the analysis of junction current. With this modification, the value of ?Bef. was found to decrease with temperature at a rate of -2.4 × 10-4 eVK-1 in approximate agreement with the known ? of the Si band gap. Attempts to model the inhomogeneous BH with a single Gaussian distribution were also successful, rendering a mean value of BH(?Bo) of 0.997 eV and a standard deviation (?o) of 0.12 eV. Similar conclusions were drawn from additional analyses, employing the modified Richardson plots. Our results suggest that the analysis of electronic transport at this and possibly other MIS junctions should include both the effect of tunnelling and that of BH inhomogeneity. © 2020 Elsevier B.V., All rights reserved.Öğe 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, IbrahimIn 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.Öğe Investigation of negative dielectric constant in Au/1 % graphene (GP) doped-Ca1.9Pr0.1Co4Ox/n-Si structures at forward biases using impedance spectroscopy analysis(Springer New York LLC barbara.b.bertram@gsk.com, 2015) Çetinkaya, Hayriye Gokcen; Alialy, Sahar; Altındal, Şemsettin; Kaya, Ahmet; Uslu, IbrahimThe dielectric properties of Au/(1 % graphene doped-Ca1.9Pr0.1Co4Ox)/n-Si structures were investigated by the impedance spectroscopy method including capacitance–voltage (C–V) and conductance–voltage (G/?–V) measurements in the frequency range of 10–2 MHz at room temperature. The experimental results show that the real and imaginary parts of dielectric constant (??, ???) and electric modulus (M? and M??), and ac electrical conductivity (?ac) are a strong functions of frequency and voltage, both. Negative dielectric constant behavior was observed at sufficiently high forward bias voltages at low frequencies and it was attributed to the interfacial polarization, interface traps and series resistance. ?? decreases with increasing frequency at sufficiently high biases whereas ??? increases. Since interfacial polarization and interface states, both, can follow the ac external signal easily at low frequencies, there occurs a contribution to the measured capacitance and conductance. The negative values of ?? correspond to maximum value of ???. Such contrary behavior in the ?? and ??? appears as an abnormality when compared to the conventional behavior metal–semiconductor structures with and without interfacial layer. Experimental results confirmed that the dielectric properties of these structures are quite sensitive to the frequency and applied bias voltage, both, especially at low frequencies and high voltages because of density distribution of interface states and interfacial polarization. © 2016 Elsevier B.V., All rights reserved.
