Yazar "Turut, Abdulmecit" seçeneğine göre listele

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    Influence of Al2O3 barrier on the interfacial electronic structure of Au/Ti/n-GaAs structures
    (Iop Publishing Ltd, 2017) Karabulut, Abdulkerim; Efeoglu, Hasan; Turut, Abdulmecit
    The Au/Ti/n-GaAs structures with and without Al2O3 interfacial layer have been fabricated. The Al2O3 interfacial layer has been formed on the GaAs substrate by atomic layer deposition. The effects of the interfacial layer on the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the devices have been investigated in the temperature range of 60-300 K. It has been seen that the carrier concentration from C-V characteristics for the MIS (metal/insulating layer/semiconductor) diode with Al2O3 interfacial layer has a higher value than that for the reference diode without the Al2O3 interfacial layer (MS). Such a difference in the doping concentration has been attributed not to doping variation in the semiconductor bulk but to the presence of the Al2O3 interfacial layer because both diodes have been made on the pieces cut from the same n-type GaAs wafer. The temperature-dependent I-V characteristics of the MIS diode do not obey the thermionic emission current theory because of the presence of the Al2O3 layer. An electron tunneling factor, a delta(chi)(1/2), value of 20.64 has been found from the I-V-T data of the MIS diode. An average value of 0.627 eV for the mean tunneling barrier height, chi, presented by the Al2O3 layer has been obtained.
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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 Characteristic Parameters of Ni/n-6H-SiC Devices Over a Wide Measurement Temperature Range
    (Springer, 2017) Ejderha, Kadir; Karabulut, Abdulkerim; Turkan, Nurettin; Turut, Abdulmecit
    Ni/n-type 6H-SiC/Ni Schottky barrier diodes (SBDs) have been prepared by the DC magnetron sputtering deposition technique. Their current-voltage characteristics (I-V) have been measured in the measurement temperature range of 40-400 K with steps of 20 K under dark conditions. The barrier height (BH) values from the temperature-dependent forward and reverse bias I-V characteristics by different methods coincide with each other which indicates the elimination of the polarity between the Si and C ions. The ideality factor value remains almost unchanged in the 160-400 K range, and below 160 K, it has the values of 1.57 at 140 K, and 3.82 at 60 K. The BH has the values of 0.79 eV at 400 K, and 0.71 eV at 300 K. The decrease in the BH is due to the fact that the current will preferentially flow through the lowest BH with decreasing temperature due to barrier inhomogeneity. The value of 0.71 eV at 300 K is in close agreement with the values of 0.65 and 0.83 eV reported from the forward bias I-V characteristics for the Ni /n-type 6H-SiC in the literature. Thus, it has been concluded that the reduced barrier devices are promising for applications in devices operating at cryogenic temperatures as infrared detectors, sensors in thermal imaging and small signal zero-bias rectifiers and microwave mixers.
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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 electrical and dielectric properties of the Au/Ti/Hf02/n-GaAs structures
    (Elsevier, 2018) Karabulut, Abdulkerim; Turut, Abdulmecit; Karatas, Sukru
    In this work, temperature dependent electrical and dielectric properties of the Au/Ti/HfO2/n-GaAs structures were investigated using capacitance-voltage (C-V) and conductance voltage (G-V) measurements in the temperature range of 60-320 K by steps of 20 K at 1 MHz. The dielectric constant (epsilon'), dielectric loss (89, dielectric loss tangent (tans) and ac electrical conductivities (sigma(ac)) have been calculated as a function of temperature. These values of the epsilon', epsilon '', tans delta and sigma(ac) have been found to be 2.272, 5.981, 2.631 and 3.32 x 10(-6) (Omega(-1)cm(-1)) at 80 K, respectively, 1.779, 2.315, 1.301 and 1.28 x 10(-6) (Omega(-1)cm(-1)), respectively at 320 K. These decrease of the dielectric parameters (epsilon', epsilon '', tans delta and sigma(ac)) have been observed at high temperatures. The experimental results show that electrical and dielectric properties are strongly temperature and bias voltage dependent. (C) 2017 Elsevier B.V. All rights reserved.
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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.