Yazar "Altindal, Semsettin" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim
    Öğe
    A comparison study regarding Al/p-Si and Al/(carbon nanofiber-PVP)/p-Si diodes: current/impedance-voltage (I/Z-V) characteristics
    (Springer Heidelberg, 2020) Sevgili, Omer; Yildirim, Mert; Azizian-Kalandaragh, Yashar; Altindal, Semsettin
    Al/p-Si and Al/(carbon nanofiber-PVP)/p-Si diodes were produced using a p-type silicon wafer with 10 omega cm resistivity to determine the polymer interlayer effects on device characteristics. To assess whether carbon nanofiber-PVP interlayer is beneficial for electrical performance, the current-voltage (I-V) and the impedance-voltage (Z-V) measurements were performed in wide range of voltage. Thus, electrical parameters such as series resistance, barrier height, and ideality factor were derived from the forward bias Ln (I-F)-V(F)and Cheung's functions, so that they are compared and voltage dependence of them is explored. Later, the values of intercept voltage, width of depletion layer, doping acceptor atom concentration, and barrier height were also extracted from C-2-Vdata at 1 MHz and then results were compared with each other. The surface states and their energy profile were also extracted from theI(F)-V(F)characteristics by considering barrier height (BH) and n is voltage dependent as well. Experimental results indicate that the carbon nanofiber-PVP interlayer decreases surface states (N-ss), series resistance (R-s) and leakage current, whereas it increases rectifying ratio and shunt resistance. Hence, such polymeric interlayer material forms an interesting alternative to conventional oxide layer due to some advantages of polymers such as desirably low values of cost, weight, and energy consumption.
  • Küçük Resim
    Öğe
    Investigation of effects on dielectric properties of different doping concentrations of Au/Gr-PVA/p-Si structures at 0.1 and 1 MHz at room temperature
    (Springer, 2020) Ersoz Demir, Gulcin; Yucedag, Ibrahim; Altindal, Semsettin
    In order to improve and detailedly investigate the dielectric properties of polymer interfaces of Metal-Polymer-Semiconductor (MPS) structures, three types of MPS were fabricated by doping 1, 3 and 5% graphene (Gr) into the polyvinyl alcohol (PVA) interface material. Capacitance-Voltage (C-V) and Conductance-Voltage (G/omega-V) measurements were used to analyze the dielectric properties of three types of MPS. UsingC-Vand G/omega-V data, series resistance (R-s) affecting device performance and interface properties besides basic dielectric parameters of each structure such as both the real and imaginary components of complex dielectric constant (epsilon'and epsilon''), complex electrical modulus (M' and M''), loss tangent (tan delta), and ac electrical conductivity (sigma(ac)) were also calculated. The effect of graphene doping was examined for each parameter and obtained results were compared at both low (0.1 MHz) and high (1 MHz) frequencies. It was observed that epsilon and epsilon'' decreased with increasing graphene doping at both 0.1 and 1 MHz, while M' and M'' increased under same conditions. Moreover, both the M' and M'' vs V plots have two distinctive peaks between -2.0 V and 0.0 V due to a special density distribution of surface states between (Gr-PVA) and p-Si. The tan delta gradually increased with increasing graphene doping at only 0.1 MHz. As the doping ratio of graphene increases, the charge carriers in the structure generate more dipoles and create an earlier relaxation process. In other words, increasing the doping ratio helps to improve the series resistance effects in MPS structures. As a result, it was seen that the interfacial properties of MPS structures were improved by increasing the rate of graphene doping.
  • Küçük Resim
    Öğe
    Investigation of the variation of dielectric properties by applying frequency and voltage to Al/(CdS-PVA)/p-Si structures
    (Elsevier, 2021) Azizian-Kalandaragh, Yashar; Yucedag, Ibrahim; Demir, Gulcin Ersoz; Altindal, Semsettin
    In this study, the effect of frequency and voltage on the dielectric properties of Al/(CdS-PVA)/p-Si structures prepared using cadmium sulfide (CdS)-polivinyl alcohol (PVA) interface material was investigated. For this purpose, real and imaginary permittivity (epsilon' and epsilon ''), dissipation factor (tan delta), ac electrical conduction mechanism (sigma(ac)), real and imaginary part of electric modulus (M' and M) were obtained by using capacitance-conductance (C-G/omega) measurements at frequency between 5kHz - 5MHz and at voltage between (-1V) - (+1V). All parameters were found to depend considerably on the frequency and voltage. epsilon' and epsilon '' reach higher values at low frequencies due to surface states (N-ss) which can easily monitor ac signal, dipolar polarization and interfacial polarization. Short-range mobility of charge carriers caused the increase of both electrical modulus and sigma(ac) with increasing frequency. Moreover, M '' exhibited a peak behavior which shifts to higher frequency with increasing voltage. Peak behavior could be ascribed to both decrease in polarization and surface states. (C) 2020 Elsevier B.V. All rights reserved.