Browsing by Author "Aydogan, S."

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Dependence of Electrical Parameters of Co/Gold-chloride Diode on Frequency and Illumination
(Elsevier, 2021) Erdogan, E.; Yilmaz, M.; Aydogan, S.; Incekara, U.; Sahin, Y.
In this study, metal-semiconductor contact with an organic interlayer was fabricated. Ideality factor (n), barrier height (phi(b)), and series resistance (R-s) values for Co/Gold-chloride/p-Si structure were calculated for dark and 100-400 mW/cm(2) light illumination intensities. The current-voltage (I-V) measurements were used to extract the electrical parameters of Co/Gold-chloride/p-Si device such as ideality factor, barrier height and series resistance using different methods like thermionic emission theory and Norde method. The n values were found in the range of 2.00-2.52 and the phi(b) were calculated in the range of 0.50-0.53 eV and under light power intensities. Additionally, frequency-dependent capacitance-voltage (C-V) measurements were done at room temperature and frequency range from 100 kHz to 1 MHz. The results show that at sufficiently high frequencies, the interface cannot flow A.C signals. Furthermore, barrier height was also calculated from the C-2-V plot for given the frequency range for Co/Gold-chloride/p-Si device. With this study, it has been shown that the rectifier contact of the organic-inorganic structure formed with suitable organic and inorganic semiconductor can be formed and this structure can be used in optoelectronic applications.
Development of a Hybrid Photodetector Device Between Pyruvic Acid (CH3COCOOH) and Silicon
(IOP Publishing Ltd, 2021) Orhan, Zeynep; Yildirim, Fatma; Taskin, Mesut; Incekara, Umit; Aydogan, S.
The authors report on the fabrication of a pyruvic acid (Pyr)/p-Si heterojunction photodetector and analyses of electro-optical behavior of the device. First, Pyr film was coated on p-Si by spin coating method. The morphology and elemental structure of this film were determined by scanning electron microscopy and energy dispersive x-ray analysis, respectively. In order to analyze the device's performance, the current-voltage (I-V) measurements were performed in the dark. The device was a rectification ratio of about 10(5) in the dark, and photodetector device parameters such as responsivity, on/off ratio and specific detectivity were analyzed in light intensity-dependent I-V measurements. Measurements depending on the light intensity were carried out between 15 and 30 mW cm(-2), at 5 mW cm(-2) intervals. The capacitance-voltage (C-V) and conductance-voltage (G-V) measurements carried out in the dark were analyzed at low and high frequencies in addition to the dielectric properties of the Pyr/p-Si heterojunction. Experimental results showed that the Pyr/p-Si device can be effectively applied to optical sensors and imaging devices.
Effects of PEDOT:PSS and Crystal Violet Interface Layers on Current-Voltage Performance of Schottky Barrier Diodes as a Function of Temperature and Variation of Diode Capacitance with Frequency
(Elsevier, 2022) Deniz, A. R.; Tas, A. I.; Caldiran, Z.; Incekara, U.; Biber, M.; Aydogan, S.; Turut, A.
In this study, diode applications of Crystal Violet (CV) and PEDOT materials were studied. The Ni/p-Si/Al, Ni/CV/p-Si/Al and Ni/PEDOT:PSS/CV/p-Si/Al diodes were fabricated. The I-V (current-voltage) characteristics of all diodes were analyzed at room temperature, it was determined that the PEDOT:PSS and CV materials improved the basic diode parameters. Also, I-V characteristics of Ni/PEDOT:PSS/CV/p-Si/Al of diode were investigated for different temperature values. It has been determined that the basic diode parameters are strongly dependent on temperature. It was determined that while the barrier height (Fb) increased with increasing temperature, the ideality factor (n) and the series resistance (Rs) values decreased. Using temperature-dependent measurements, it was determined that the potential barrier and ideality factor values at the contact interface has a double Gaussian distribution. In addition, C-V (capacitance-voltage) measurements of these diodes were analyzed depending on the frequency. It was found that the diode capacitance decreased with increasing frequency.
Enhanced Photoresponse in MIS-Type UV-Vis Photodetector via Biocompatible Glutathione(C10H17N3O6S) Interlayer: Theoretical and Experimental Analysis
(Springer Nature, 2025) Yildirim, F.; Taskin, M.; Ben Ahmed, A.; Benhaliliba, M.; Incekara, U.; Aydogan, S.
Commercially available glutathione (GSH) compound isspin coated on n-Si wafer to passivate the surface of Si. The optical absorption and SEM analysis of the GSH film are performed. The optical bandgap energy of the GSH and the fundamental bandgap energy are equal to 5.526 eV and 6.325 eV, respectively. GSH presents much lower value of binding energy. It isobserved that the Au/GSH/n-Si MIS junction exhibited both a dark-rectifying ratio of 3370 and an excellent photoresponse in the visible light, UV and IR regions. Comparing the Au/GSH/n-Si junction with the Au/n-Si diode, the reverse current of the device containing the GSH interlayer decreased by more than 3 orders of magnitude. Since the low reverse current is essential for high performance in photodetectors, the photoresponse analysis of the device isinvestigated in detail. The highest responsivity and detectivity values under 365 nm UV light are 53.18 mA/W and 2.18 x 1011 Jones, respectively. Time-dependent I-V characteristics showed that the MIS device photosensitive device maintained its stability even after 110 days. These experimental results show that the Au/GSH/n-Si MIS photodetector has the potential for optical signal communication in a wide wavelength region.
Influence of Thickness of the Sputtered Diamond-Like Carbon (Dlc) on Electronic and Dielectric Parameters of the Au/Dlc Heterojunction
(Springer, 2021) Kurt, Mustafa Sukru; Yildirim, Fatma; Orhan, Zeynep; Aydogan, S.
The electrical and dielectric properties of the Au/DLC/n-Si heterojunction were investigated in detail by coating the diamond-like carbon (DLC) layers of different thicknesses on Si by the magnetron sputtering. The influence of DLC thickness on the Au/DLC/n-Si heterojunction is the main objective of the study. For this purpose, the current-voltage measurements of the heterojunction were performed as a function of the thickness (10 (D1), 20 (D2), and 50 nm (D3) DLC layer) and it was seen that the device with 50 nm thickness had the best rectifying property (the lowest ideality factor) and stable reverse current, the lowest interface states, the highest dielectric parameter (K), and shunt resistances. And then the capacitance/conductance versus voltage measurements of the heterojunctions were carried out to determine the electrical and dielectric properties of the devices at 500 kHz applied frequency. Some improvements in the high dielectric parameter D3 device were attributed to further limitation of the leakage current. The experimental results suggested that both the complex dielectric parameter (K*) and loss tangent (tan delta) were a function of the bias voltage and frequency due to the existence of the surface states and dipole polarizations. Experimental results showed that the DLC layer causes surface passivation on Si, resulting in improved device with increasing thickness, and the DLC/n-Si device is a candidate device for high voltage applications.
An Investigation of Spray Deposited CdO Films and CdO/P-Si Heterojunction at Different Substrate Temperatures
(Springer, 2021) Turgut, G.; Aydogan, S.; Yilmaz, M.; Ozmen, A.; Kacus, H.
In this study, CdO films were successfully obtained by using a homemade chemical spray pyrolysis technique. The crystal structures of the CdO thin films improved due to an increase in the substrate temperature when the spray time was kept constant. Additionally, CdO film deposited at 250 degrees C exhibited amorphous crystal structure. The surface morphology of the samples was evaluated by scanning electron microscope (SEM) and it was observed that well-defined granules started to be clearly seen when the substrate temperature increased. Optical properties of CdO films were also investigated by using an ultraviolet-visible (UV-Vis) spectrophotometer, and the optical band gap of CdO varied from 2.57 eV to 2.73 eV with increasing substrate temperature. The electrical performance of the CdO films in the Au/CdO/p-Si device were determined by I-V measurements. According to the results, it was found that diode parameters depend on the changing properties of CdO in terms of the substrate temperature.
An Investigation of Spray Deposited Cdo Films and Cdo/P-si Heterojunction at Different Substrate Temperatures (Vol 73, Pg 566, 2021)
(Springer, 2021) Turgut, G.; Aydogan, S.; Yilmaz, M.; Ozmen, A.; Kacus, H.
This article was corrected to remove extraneous units of eV for ideality factor introduced during the production process.
Modification of Barrier Diode with Cationic Dye for High Power Applications
(Elsevier GmbH, 2021) Erdogan, E.; Yilmaz, M.; Aydogan, S.; Incekara, U.; Kacus, H.
Current-voltage (I-V) measurements of Au/methylene blue (MB)/p-Si/Al diode were taken at room temperature, in the dark and under illumination and also in a wide temperature range (100-360 K). Schottky diode showed non-ideal current-voltage behavior at 360 K and 100 K with ideality factors (n) equal to 1.81-1.46 and 3.52-2.73, respectively, using TE and Cheung methods. Experimental barrier height (phi(b)) values of the diode were determined as 0.29 eV for TE, 0.33 eV for Cheung and 0.38 eV for Norde at 100 K, and 0.79, 0.81, and 0.87 eV at 360 K, respectively. Series resistance (R-s) was found with the help of Cheung functions and Norde functions. The results show that the produced diode can be used in a variety of optoelectronic applications.
On the Investigation of the Electro-Optical Sensor Potential of Boswellia Serrata Resin
(Elsevier, 2021) Yildirim, Fatma; Yilmaz, Mehmet; Incekara, Umit; Aydogan, S.
In a first step, Boswellia serrata (Bs) resin was purchased in its natural state and dissolved in deionized water and coated on the n-Si wafer by spin coating method as a thin film with about 1 mu m. SEM images and EDX analyses of Bs resin film on the n-Si wafer were obtained. It has been seen that the fabricated Bs/n-Si device has an unsymmetrical current-voltage (I-V) graph and a good rectifier feature. Then, we analyzed some electrical characteristics of Bs/n-Silicon heterojunction. Using light intensity-dependent (in the range of 100-250 mW/cm2) current-voltage (I-V) and in dark, capacitance-conductance-voltage (C-G-V) and capacitance-frequency (C-f) measurements of Bs/n-Si heterojunction were investigated. The heterojunction shows a photodiode behavior such that the reverse-bias photocurrent exceeds the dark reverse current and the reverse bias current increased linearly with increasing light intensity. Hence, we determined the sensitivity, responsivity, detectivity and main rectifying junction parameters such as rectifying ratio, ideality factor, barrier height, and series resistance. Furthermore, the barrier heights from the reverse bias C-V measurements were determined and it was found to depend on the frequency. In forward biases, the C decreased with increasing frequency while G increased. In summary, it was concluded that Bs forming a p-n heterostructure with n-Si is a potential material for optoelectronic applications.
Photo-Sensor Characteristics of Tannic Acid (C76H52O46)/N-Si Hybrid Bio-Photodiode for Visible and UV Lights Detection
(Elsevier Sci Ltd, 2022) Yildirim, Fatma; Orhan, Zeynep; Taskin, Mesut; Incekara, Umit; Biber, Mehmet; Aydogan, S.
We present the electo-optical characterization of tannic acid (TA)/n-Si heterojunction for visible and UV lights (365 nm and 395 nm). The TA was deposited on n-Si by spin coating. The morphological and structural analyses of TA film were carried out by Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray (EDX) analyses, respectively. The electro-optical performance of the TA/n-Si bio-photodiode were investigated by I-V measurements for 10 mW/cm(2), 15 mW/cm(2), 20 mW/cm(2) and 30 mW/cm(2) visible light intensities in addition to UV light. Light-dependent the responsivity, ON/OFF ratio, detectivity, shunt resistance and series resistance were calculated. Maximum values of responsivity, detectivity and ON/OFF ratio were determined as 11.9 mA/W (-1.5 V), 3.2 x 109 Jones (at-0.42 V) and 194 (30 mW/cm2) (AM 1.5 G), at-2 V respectively. Whereas, they were determined to be 0.1 A/W, 4 x 109 Jones and 14977, respectively for UV light. Furthermore, the dielectric properties of the TA/n-Si heterostructure also were investigated from the dark Capacitance/Conductance-Voltage measurements. It was seen that both real and imaginary parts of the dielectric constants was frequency dependent. Experimental results show that the TA/n-Si device with a high rectification ratio of 2263 is a potential candidate for detecting visible and UV lights.