Browsing by Author "Karabulut, A."

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Effect of Atomic-Layer HfO2 Thin-Film Interfacial Layer on the Electrical Properties of Au/Ti Schottky Diode
(Springer, 2021) Yildiz, D. E.; Karabulut, A.; Orak, I.; Turut, A.
The electrical properties of Au/Ti/HfO2/n-GaAs metal/insulating layer/semiconductor (MIS) contact structures were analyzed in detail by the help of capacitance-voltage (C-V) and conductance-voltage (G-V) measurements in the temperature range of 60-320 K. The HfO2 thin-film layer was obtained by atomic layer deposition technique (ALD). The main electrical parameters such as ideality factor (n) and barrier height (Phi(B0)) were determined for Au/Ti/n-GaAs and Au/Ti/HfO2/n-GaAs diodes using current-voltage (I-V) measurement at 300 K. The values of these parameters are 1.07 and 0.77 eV for the reference (Au/Ti/n-GaAs) diode and 1.30 and 0.94 eV for the Au/Ti/HfO2/n-GaAs MIS diode, respectively. An interfacial charge density value of Q(ss) = 4.14 x 10(12) Ccm(-2) for the MIS diode was calculated from the barrier height difference of Delta Phi = 0.94 - 0.77 = 0.17V. Depending on these results, the temperature-dependent C-V and G-V plots of the device were also investigated. The series resistance (R-s), phase angle, the interface state density (D-it), the real impedance (Z') and imaginary impedance (Z '') were evaluated using admittance measurements. The C and G values increased, whereas (Z '') and Z decreased with increasing voltage at each temperature. An intersection point being independent of temperature in the G-V curves appeared at forward-bias side (approximate to 1.4 V); after this intersection point of the G-V plot, the G values decreased with increasing temperature at a given voltage. The intersection points in total Z versus V curves appeared at forward-bias side (approximate to 1.7 V). The Nyquist spectra were recorded for the MIS structure showing single semicircular arcs with different diameters depending on temperature.
Effect of Illumination on Electrical Characteristics of Au/Mn-Complex Photodiode Structures
(Springer, 2022) Baris, B.; Yildirim, M.; Karadeniz, S.; Karabulut, A.; Kose, A.; Yildiz, D. E.
We were produced a various Mn-doped complex and presented it in Au/Mn-complex/n-Si structure as an interfacial layer. For this aim, a metal-nicotinate/nicotinamide mixed ligand complex was synthesized with Mn dopant. Surface morphologies were investigated using surface analysis methods (AFM and SEM) and relatively smooth and uniform surfaces were obtained for each doping level. The devices were characterized using current-voltage and time-dependent photoresponse measurements. In order to examine the response to light, the measurements were carried out in the dark and different lighting (from 20 to 100 mW/cm(2)) intensities. With the increasing amount of Mn dopant, the barrier heights and junction resistance of devices were decreased. Increasing the amount of light was increased the sensitivity of the devices to the light. The highest photoconductivity was recorded for 1 mg Mn-complex. It was seen from obtained results, the fabricated devices exhibited good photodiode behavior and can be used in optoelectronic applications.
Electrical Characteristics of Atomic Layer Deposited Au/Ti MIS Diodes in the Wide Temperature Range
(Springer, 2020) Turut, A.; Yildiz, D. E.; Karabulut, A.; Orak, I.
Au/Ti/HfO2/n-GaAs MIS (metal/insulating layer/semiconductor) diodes were fabricated by atomic layer deposition technique and their electrical properties were investigated in detail by the help of current-voltage (I-V) and admittance measurements in the temperature range of 60-320 K. Together with the surface morphology analysis on the HfO2 thin-film layer, main electrical parameters such as series resistance (R-s), zero bias barrier height (phi(Bo)), ideality factor (n), impedance (Z) and phase angle were determined and effects of temperature on these parameters of the MIS diodes were discussed. The evaluation of I-V data exhibits a decrease in R-s and phi(Bo), however an increase in n, with a decrease in temperature. Temperature-dependent conductance (G) and capacitance (C) characteristics of the MIS diode were investigated at 1000 kHz in the voltage interval in between - 3 and 2 V. G and C values were found in a direct relation with the change in temperature. On the other hand, Z values showed an inverse proportionality with temperature. The phase angle versus voltage plots were evaluated at different temperatures (60-320 K) at 1000 kHz and the obtained results indicated that the device behaves more capacitive in the voltage range of - 3 V and about 0.4 V for all temperature, and phase angle decreases with increasing temperature from 0.4 to 1.6 V. In addition, the interface state density (D-it), the effective oxide charge density (Q(eff)) and effective number of charges per unit area (N-eff) of the fabricated diodes were investigated over temperature range 60-320 K in which these values were found in a decreasing trend with increasing temperature.
Illumination Impact on the Electrical Characteristics of Au/Sunset Yellow/N-Si Hybrid Schottky Diode
(Springer, 2020) Imer, A. G.; Kaya, E.; Dere, A.; Al-Sehemi, A. G.; Al-Ghamdi, A. A.; Karabulut, A.; Yakuphanoglu, F.
In this study, semiconductor device applications of organic material sunset yellow (SY) (C16H10N2Na2O7S2) has been investigated. The SY thin film was grown onn-Si via spin coating method and theAu/SY/n-Si/Auheterojunction was fabricated. The basic diode parameters of device were determined by the current-voltage (I-V) and capacitance-voltage (C-V) measurements at the room temperature. The values of the ideality factory (n) and barrier height (phi(b)) were evaluated as 1.15 and 0.70 eV, respectively; and series resistance (R-s) of device was found using Norde functions. The values of built in potential, donor concentration, Fermi energy level and barrier height were also estimated from the linearC(-2)-Vcurves with reverse bias room temperature and difference frequency. Furthermore,I-Vmeasurements were applied under different illuminations; some photoelectrical parameters of device were evaluated to understand the photo response properties of the device. Consequently, the results confirmed that the barrier height can be modified by interfacial SY layer, and the device can be used in optoelectronic applications such as optical sensor or photodiode.