Browsing by Author "Öztürk Ö."

Now showing 1 - 5 of 5

Comparative investigation on electronic properties of metal-semiconductor structures with variable ZnO thin film thickness for sensor applications
(2019-10-01) Çiçek O.; Kurnaz S.; Bekar A.; Öztürk Ö.
In this work, AuPd/n-GaAs and Ag/n-GaAs metal–semiconductor structures, which is known as Schottky Junction Structures (SJSs), with various ZnO thin film thickness (25–250 nm) classified as Group AuPd and Group Ag were produced to investigate electronic properties on SJSs. The current-voltage (I–V) characteristics of SJSs operating in their forward and reverse regions operating at ±3 V were measured at room temperature (295 K). The electronics parameters such as the series resistance (Rs), the shunt resistance (Rsh), the ideality factor (n) and the barrier height (ΦB0) were calculated by using thermionic emission (TE) theory, Ohm's law, Cheung and Cheung's function and modified Norde's function. Labview® based characterization tool developed to calculate the electronic parameters. The results were compared according to the various thicknesses and different rectifier contacts. Experimentally, if the results are analysed for each group, a (gradual) decrease in ZnO thicknesses is caused by an increase in the values of n, ФB0, RR. In addition, the Rsh values were significantly increased while the Rs values were almost close to each other. As the ΦB0 values, while compatible with the values found in the Cheung and Cheung's function, they are slightly higher than the values found in the TE theory. On the other hand, due to the voltage-dependent barrier height and nature of the used method, ФB0 values from modified Norde's function are a little higher than the TE theory. Finally, it can be clearly seen that electronic parameters of SJSs based on sensor applications can be arranged with various thicknesses according to extracted results.
İnfluence Of Diffusion Annealing Temperature On Physical And Mechanical Properties İn Au Diffusion Doped Bi 2223 Superconductors
(2008) Öztürk Ö.; Kılıçaslan F.; Hançerlioğulları A.; Terzioğlu C.; Belenli İ.
Investigation of microhardness properties of the multi-walled carbon nanotube additive MgB2 structure by using the vickers method
(2021-06-01) Kaya N.; Çavdar Ş.; Öztürk Ö.; Ada H.; Koralay H.
In this study, the effect of multi-walled carbon nanotube doping to MgB2 compound on microhardness properties of MgB2 was investigated by using solid-state reaction method. The amount of multi-walled carbon nanotubes was chosen as 0, 1, 2, 3 and 4% by weight of total MgB2. All samples were obtained by sintered at 650 °C temperatures. The microhardness properties of the samples obtained were examined using the Vickers method. At the same time, the samples obtained were analyzed according to Meyer's Law, proportional sample resistance (PSR) model, Hays-Kendall (HK) approach and elastic/plastic deformation (EPD) model. Samples were found to exhibit indentation size effect (ISE) behavior. It was understood that the multi-walled carbon nanotubes doped to the samples made MgB2 softer by reducing the intergranular bonding of the MgB2 structure. In addition, it was found that the force applied to the samples caused both plastic and elastic deformation on the samples.
Self-powered visible-UV light photodiodes based on ZnO nanorods-silicon heterojunctions with surface modification and structural enhancement
(2022-07-01) Çiçek O.; Karasüleymanoğlu M.; Kurnaz S.; Öztürk Ö.; Taşçı A.T.
The letter reports the visible-UV light response of Al/ZnONRs/ZnOseed/p-Si/Al type photodiodes (PDs) with surface modification and structural enhancement. The PDs, which are referred to as PD10–2, PD10–4, PD20–2, PD20–3, and PD20–4 according to molar concentration (mM) and time (hour), were produced for improving the performances. Basic electronic parameters were obtained from the I-V data of Al/ZnONRs/ZnOseed/p-Si/Al type PDs by using thermionic emission (TE) theory, Ohm's law, and Cheung's methods. In accordance with the literature, the results showed that the potential barrier height (ФBo) values decreased with the increasing illumination intensity, while the ideality factor (n) values increased. In addition, voltage-dependent series resistance (Rs) values of the PDs under dark and different visible-UV light intensities were calculated by using Ohm's law and Cheung's method. It was observed that the Rs values decreased with increasing light intensities. On the other hand, the photosensitivity characteristics of the PDs at visible-UV light intensities were investigated depending on the applied voltage. While the photosensitivity value of the produced PD10–2 device reached the maximum value of 6.9 × 103 at the short-circuit voltage Vsc= 0 V, the open-circuit voltage Voc showed better photosensitivity with a minimum value of 0.0702 in the self-powered mode. In addition, the responsivity (R) and the detectivity (D*) values of Al/ZnONRs/ZnOseed/p-Si/Al type PDs were calculated. Herein, the R and D* values decreased with increasing power density at zero-bias voltage in accordance with the literature. Also, the R and D* values of the PD10–2 device are higher and lower than other devices, respectively. The linear dynamic range (LDR) value of the PD10–2 device reaches ~78 dB with a maximum value at Vbias= 0 V, while the dark current is 0.21 nA with a minimum value, self-powered mode. It is concluded that the PD10–2 device is suitable for photodiode applications in self-powered mode.
The Nucleation Effect of PbSe Additive on Bi2Sr2CaCu2Oδ Glass Ceramics
(2022-05-01) Çavdar Ş.; Deniz E.; Turan N.; Taşçı A.T.; Öztürk Ö.; Koralay H.
The crystallisation kinetics and effects of doping on Bi2Sr2CaCu2Oδ (BSCCO) glass ceramic system with 0.0%, 0.1%, 0.3% and 0.5% PbSe were investigated in this study. Differential thermal analysis (DTA) was used to investigate the effects of PbSe doping on glass transition, nucleation and crystallisation temperature of glass were investigated. The DTA results were analysed using the Ozawa, Augis–Bennett, Takhor and Kissinger equations for nucleation kinetics to determine the activation energies and Avrami parameters. Thermogravimetric analysis revealed that the amount of oxidation in the structure increased with increasing PbSe-doping concentration.