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    A novel device fabricated with Cu2NiSnS4 chalcogenide: Morphological and temperature-dependent electrical characterizations
    (Elsevier, 2020) Karabulut, Abdulkerim; Sarilmaz, Adem; Ozel, Faruk; Orak, Ikram; Sahinkaya, Mehmet Akif
    Cu2NiSnS4 nanorods were synthesized by the usage of hot-injection technique and used as interlayer between the p-Si and Al metal in order to examine their behavior against the temperature and frequency changes. The current-voltage measurements were performed in 80-300 K temperature range with 20 K steps. The X-Ray Diffraction (XRD) was used to prove the crystal structure of the synthesized Cu2NiSnS4 nanorods. Some crucial device parameters such as barrier height, series resistance and ideality factor values were calculated, and the obtained values were compared with other studies in the literature. It has been seen that the calculated parameters of the prepared device are strongly dependent on temperature changes. Besides, the capacitor behavior of fabricated device was investigated depending on the frequency and voltage changes. The experimental results indicated that the prepared device with Cu2NiSnS4 nanorods interlayer could be utilized in the electronic technology, especially applications in wide temperature range.
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    Frequency and voltage dependence of electrical conductivity, complex electric modulus, and dielectric properties of Al/Alq3/p-Si structure
    (Tubitak Scientific & Technological Research Council Turkey, 2020) Orak, Ikram; Karabulut, Abdulkerim
    In order to enhance the capacitance of the Al/p-Si metal-semiconductor structure, the Alq(3) thin film was coated between these two layers using the spin coating technique as the interlayer. The electrical conductivity, real and imaginary parts of electric modulus, dielectric loss and dielectric constant parameters were examined at the room temperature by the help of admittance measurements in the 100 kHz to 1 MHz frequency range. The effect of frequency on the dielectric constant and dielectric loss values is negligible at the negative voltage values, up to about 0.8 V, and these values rapidly ascended after 0.8 V. The function of electrical modulus complex has been examined from the point of permittivity and impedance in order to clutch the contribution of the particle border on the relaxation mechanism of the materials. It is established that the examined dielectric parameters strongly correlated with the voltage and frequency. As a result, the changes in the dielectric parameters and electrical modulus due to the varying frequency were described as the results of relaxation process, polarization and surface conditions. Furthermore, it could be stated that the Alq(3) material used in the interfacial layer is a useful material which could be used in addition to the conventional materials.
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    Temperature-dependent electrical characteristics of Alq3/p-Si heterojunction
    (Elsevier Science Bv, 2018) Karabulut, Abdulkerim; Orak, Ikram; Canli, Serdal; Yildirim, Nezir; Turut, Abdulmecit
    Al/Alq3(organic materials)/p-Si device was fabricated by the use of spin coaling technique, and it was investigated by using current-voltage measurement in a wide temperature range from 80 to 320 K with 20 K steps. Some device parameters such as ideality factor, barrier height and series resistance values were determined by the use of standard thermionic emission theory and Norde functions, and the values found were compared with other studies. It was seen that all parameters of fabricated device strongly depended on temperature changes. AFM and SEM images were taken for better understanding surface morphology, and addressed in detail. The results of experiments suggest that the fabricated device with Alq3 organic interfacial layer could be used effectively in the temperature-dependent device applications for developing electronic technology.
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    THE CURRENT-VOLTAGE CHARACTERISTICS OVER THE MEASUREMENT TEMPERATURE OF 60-400 K IN THE Au/Ti/n-GaAs CONTACTS WITH HIGH DIELECTRIC HfO2 INTERFACIAL LAYER
    (World Scientific Publ Co Pte Ltd, 2019) Karabulut, Abdulkerim; Orak, Ikram; Caglar, Mujdat; Turut, Abdulmecit
    The Au/Ti/HfO2/n-GaAs metal/insulating layer/semiconductor structures have been fabricated using standard thermal atomic layer deposition. We experimentally showed whether or not the HfO2 interfacial layer grown on the n-GaAs wafer modifies the barrier height (BH) of the device at the room temperature. Besides, we investigated the measurement based on temperature dependence of the device parameters from the current-voltage (I-V) characteristics of the diode in 60-400 K range with steps of 10 K. The X-ray photoelectron spectroscopy (XPS) have been carried out to characterize the surfaces of both n-GaAs wafer and HfO2 thin films. The series resistance value from the temperature-dependent I-V characteristics decreased with decreasing temperature, which is a desired positive result for the devices developed from the MOS capacitor. The BH value of 0.94 eV (300 K) has been obtained for the device with the HfO2 layer which is a higher value than the value of 0.77 eV (300 K) of the device without HfO2 layer. Therefore, we can say that the HfO2 thin layer at the metal/GaAs interface can also be used for the BH modification as a gate insulator for GaAs MOS capacitor and MOSFETs. When the temperature-dependent I-V characteristics at low temperatures have been considered, it has been observed that the current prefers to flow through the lowest BHs due to the BH inhomogeneities.
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    The effects of temperature and frequency changes on the electrical characteristics of hot-injected Cu2MnSnS4 chalcogenide-based heterojunction
    (Elsevier, 2020) Sarilmaz, Adem; Ozel, Faruk; Karabulut, Abdulkerim; Orak, Ikram; Sahinkaya, Mehmet Akif
    Cu2MnSnS4 chalcogenide was obtained with the help of hot-injection technique and used as an interfacial thin layer to examine its behavior under varying temperature and frequency conditions. The well-known XRD, SEM and EDX techniques were utilized in the analysis of structural and content. To investigate the electrical properties, the variations in current, capacitance, conductance and impedance depending on the changing voltage were investigated. In the current-voltage measurements, measurements were made in distinct temperatures in addition to room temperature, and the effect of the temperature on the basic electrical parameters such as barrier height and ideality factor was investigated. The results showed that the temperature significantly affected the electrical properties. However, capacitance, impedance and conductance measurements were carried out for various frequencies. The performed experiments indicate that the fabricated heterojunction-based device using Cu2MnSnS4 chalcogenide could be evaluated in the wide temperature applications and enhanced as a capacitor in the electronic technology.
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    The photovoltaic impact of atomic layer deposited TiO2 interfacial layer on Si-based photodiodes
    (Pergamon-Elsevier Science Ltd, 2018) Karabulut, Abdulkerim; Orak, Ikram; Turut, Abdulmecit
    In present work, photocurrent, current- voltage (I-V) and capacitance/conductance-voltage- frequency (C/G-V-f) measurements were analyzed for the photodiode and diode parameters of Al/TiO2/p-Si structure. The TiO2 thin film structure was deposited on p-Si by using atomic layer deposition technique (ALD) and its thickness was about 10 nm. The surface morphology of TiO2 coated on p-Si structure was observed via atomic force microscope (AFM). Barrier height (Phi(b)) and ideality factor (n) values of device were found to be 0.80 eV, 0.70 eV, 0.56 eV and 1.04, 2.24, 10.27 under dark, 10 and 100 mW/cm(2), respectively. Some photodiodes parameters such as fill factor (FF), power efficiency (%eta), open circuit voltage (V-oc), short circuit current (I-sc) were obtained from I-V measurement under different light intensity. FF and. were accounted 49.2, 39,0 and 0.05, 0.45 under 10 and 100 mW/cm(2) light power intensity, respectively. C-2-V graph was plotted from C-V-f measurements and zero bias voltage (V-0), donor concentration (N-d), Fermi energy (E-F), barrier height (Phi(b)) and maximum electric field (E-m) were determined from C-2-V data for different frequencies. The electrical and photocurrent values demonstrated that it can be used for photodiode, photo detector and photo sensing applications.
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    The synthesis of new bola-amphiphile TPEs and the comparison of current transformer mechanism and structural properties for Al/Bis(HCTA)-TPE/p-Si and Al/Bis(HCOA)-TPE/p-Si heterojunctions
    (Elsevier Sci Ltd, 2019) Sevgili, Omer; Lafzi, Ferruh; Karabulut, Abdulkerim; Orak, Ikram; Bayindir, Sinan
    In this study, the new bola-amphiphile tetraphenylethylene derivatives Bis(HCTA)-TPE and Bis(HCOA)-TPE were synthesized to use in device application by a green approach. Al/organic layer/p-Si heterojunctions were fabricated by the usage of Bis(HCTA)-TPE and Bis(HCOA)-TPE organic interfacial layers. The mentioned organic layers were coated on the polished side of silicon wafer using the spin coating method. The surface and morphological analyses of materials coated on silicon substrate were investigated by using atomic force microscopy (AFM) and scanning electron microscopy (SEM) images. Besides, the electrical characteristics of fabricated heterojunctions were examined by the use of current-voltage (I-V) and current-time (I-t) measurements and compared with each other. characteristics were investigated under various illumination conditions, and also the behavior of these characteristics against changing temperature conditions has been determined. At the same time, transient photocurrent measurements were performed to determine the photo response behaviors. The results show that the fabricated device with Bis(HCTA)-TPE organic interfacial layer exhibits better electrical characteristics than the Bis(HCOA)-TPE organic layer. The other result of this experiment is that the fabricated devices could be used in optoelectronic and photovoltaic applications.