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1
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Electronic and Photovoltaic Properties of p-Si/PCBM:MEH-PPV Organic-Inorganic Hybrid Photodiode

100%
Yakuphanoglu F., Farooq W.
Acta Physica Polonica A
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2011
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vol. 119
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issue 6
890-894
EN
The photovoltaic and electronic properties of p-Si/poly[2-methoxy,5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV):[6, 6]-phenyl C_{61}-butyric acid methyl ester (PCBM) organic-inorganic device have been investigated. The current-voltage characteristic of p-Si/PCBM:MEH-PPV photodiode includes series resistance effect and the diode indicates a non-ideal behavior. The photovoltaic effect in p-Si/PCBM:MEH-PPV photodiode is based on the formation of excitons and subsequent dissociation and charge collection at the electrodes. It is evaluated that p-Si/PCBM:MEH-PPV device is a photodiode with V_{oc} of 84 mV and I_{sc} of 3.47 nA electronic parameters.
2
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Electrical and Interfacial Properties of p-Si/P3HT Organic-on-Inorganic Junction Barrier

81%
Yakuphanoglu F., Shah M., Aslam Farooq W.
Acta Physica Polonica A
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2011
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vol. 120
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issue 3
558-562
EN
The electrical characterization of the Al/p-Si/P3HT/Ag organic-on-inorganic diode was done by current-voltage, capacitance-voltage and conductance-voltage methods. The values of ideality factor and barrier height of the diode were determined from the current-voltage characteristics and found as 2.32 and 0.77 eV, respectively. These values were also determined from Cheung's functions and Norde's method due to the non-ideal behavior of the diode. The electronic parameters obtained from the various methods indicate a good consistency with each other. The density of interface states for Al/p-Si/P3HT/Ag organic-on-inorganic diode was found to be 7.64 × 10^{10} cm^{-2} eV^{-1}. The obtained electrical parameters of the Al/p-Si/P3HT/Ag organic-on-inorganic diode are higher than that of the conventional Ag/p-Si Schottky diodes. This indicates that the electrical properties of the silicon Schottky diodes can be controlled using organic interfacial layer.
3
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Controlling of Transformation Temperatures of Cu-Al-Mn Shape Memory Alloys by Chemical Composition

81%
Aksu Canbay C., Karagoz Z., Yakuphanoglu F.
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vol. 125
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issue 5
1163-1166
EN
The Cu-Al-Mn shape memory alloys having various chemical compositions were prepared by arc melting method to control the phase transformation parameters. The phase transformation parameters and structural properties of the alloys were investigated by differential scanning calorimetry and optic microscopy, respectively. The effects of the chemical composition on characteristic transformation temperatures, enthalpy and entropy values of Cu-Al-Mn ternary system were investigated. The characteristic transformation temperatures of austenite and martensite phase (A_{s}, A_{f}, M_{s}, and M_{f}) are increased with change in the chemical composition of the alloys. The average crystallite size for the alloys was calculated to determine the effect of aluminum and manganese compositions on the transformation temperatures. The change in transformation temperatures indicates the same trend with change in crystallite size. The obtained results suggest that the phase transformation parameters of the Cu-Al-Mn alloys can be controlled by Al and Mn contents.
4
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Effects of La Dopant on Nanocluster Size and Optical Band Gap of CdO Films Prepared by Sol-Gel Method

81%
Alahmed Z., Serbetçi Z., Yakuphanoglu F.
Acta Physica Polonica A
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2013
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vol. 124
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issue 1
125-127
EN
The undoped and lanthanum doped cadmium oxide thin films were prepared by sol-gel method. The CdO films were doped with various percentages of La, 0.1, 0.5, 1, and 2 at.%. We have investigated the structural properties of the CdO films by atomic force microscopy. The obtained results show that both the grain size and the surface roughness of CdO films reduce with increase of La doping content. Additionally, the result shows a significant decrease of the transmittance in the range of 300 to 500 nm with increase of La doping level. The optical band gap of CdO films increases with La doped CdO films. It was found that the band gaps to be 2.25, 2.36, 2.4, 2.28, and 2.31 eV for La contents with 0.1, 0.5, 1, and 2 at.% doped CdO, respectively.
5
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Improvement of Efficiency in CdS Quantum Dots Sensitized Solar Cells

62%
Wageh S., Al-Ghamdi A., Soylu M., Al-Turki Y., El Shirbeeny W., Yakuphanoglu F.
Acta Physica Polonica A
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2013
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vol. 124
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issue 4
750-754
EN
CdS quantum dots were coated on TiO_2 layer by successive ionic layer adsorption and reaction method. An efficient photovoltaic energy conversion and significant quantum-size effect were observed. The magnitude of the short-circuit photocurrent density J_{SC} was found to be approximately 6.01 mA/cm^2 for graphene oxide-incorporated CdS/TiO_2 solar cell, while the J_{SC} of only CdS-sensitized solar cells was lower than 4.40 mA/cm^2. The efficiency of the CdS/TiO_2 solar cell with a graphene oxide layer containing CdS QDs was 60% higher than that of the CdS/TiO_2 solar cell. The cell efficiency was remarkably improved with the graphene oxide-incorporation. The carrier recombination of the QDs sensitized solar cells based on CdS-coated TiO_2 was significantly suppressed due to photogenerated charge carrier transports resulting from the presence of graphene oxide.
6
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Impedance Spectroscopy of Nanostructure p-ZnGa_{2}Se_{4}/n-Si Heterojunction Diode

62%
Yahia I., Fadel M., Sakr G., Shenouda S., Yakuphanoglu F., Farooq W.
Acta Physica Polonica A
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2011
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vol. 120
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issue 3
563-566
EN
The impedance characteristics of the nanostructure p-ZnGa_2Se_4/n-Si heterojunction diode were investigated by impedance spectroscopy method in the temperature range (303-503 K) and the frequency range (42 Hz-5 MHz). The real and imaginary parts of the complex impedance are changed with the frequency. Both are decreased with increasing temperature at the lower frequencies and are merged at the higher frequencies. The dielectrical relaxation mechanism of the diode was analyzed by the Cole-Cole plots. The Cole-Cole plots under various temperatures exhibit one relaxation mechanism. With increasing temperature, the radius of the Cole-Cole plots decreases, which suggests a mechanism of temperature-dependent on relaxation.
7
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A DNA Biosensor Based Interface States of a Metal-Insulator-Semiconductor Diode for Biotechnology Applications

62%
Al-Ghamdi A., Al-Hartomy O., Gupta R., El-Tantawy F., Taskan E., Hasar H., Yakuphanoglu F.
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EN
We studied how a DNA sensor based on the interface states of a conventional metal-insulator-semiconductor diode can be prepared for biotechnology applications. For this purpose, the p-type silicon/metal diodes were prepared using SiO_2 and DNA layers. The obtained results were analyzed and compared with interfaces of DNA and SiO_2. It is seen that the ideality factor (1.82) of the Al/p-Si/SiO_2/DNA/Ag diode is lower than that (3.31) of the Al/p-Si/SiO_2/Ag diode. This indicates that the electronic performance of DNA/Si junction was better than that of SiO_2/Si junction. The interface states of the Al/p-Si/SiO_2/DNA/Ag and Al/p-Si/SiO_2/Ag junctions were analyzed by conductance technique. The obtained D_{it} values indicate that the DNA layer is an effective parameter to control the interface states of the conventional Si based on metal/semiconductor contacts. Results exhibited that DNA based metal-insulator-semiconductor diode could be used as DNA sensor for biotechnology applications.
8
Content available remote

Controlling of Optical Band Gap of Allyl Diglycol Carbonate Polymer with Ultraviolet Laser Radiation

62%
Farooq W., Baig M., Fatehmulla A., Al-Salhi M., Al-Ghamdi S., Yakuphanoglu F.
Acta Physica Polonica A
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2013
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vol. 123
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issue 1
106-110
EN
The effects of ultraviolet laser radiation on the structure and optical properties of allyl diglycol carbonate have been investigated. The allyl diglycol carbonate samples were irradiated with 266 nm with different power densities from Nd:YAG laser. The bulk etch rate enhancement and enlargement of track diameter clearly indicate that allyl diglycol carbonate is significantly affected by UV laser. The laser-irradiated allyl diglycol carbonate samples showed a decrease in the optical band gap with increasing laser power density. The obtained results indicate that the optical band gap of the alpha irradiated polymer is varied from 4.10 eV to 2.65 eV by UV laser irradiation.
9
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Determination of Optical Constants of Nanocluster CdO Thin Films Deposited by Sol-Gel Technique

52%
Serbetci Z., Gunduz B., Al-Ghamdi A., Al-Hazmic F., Arık K., El-Tantawy F., Yakuphanoglu F., Farooq W.
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vol. 126
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issue 3
798-808
EN
The optical properties of the CdO and Pt doped CdO thin films synthesized by sol-gel technique were investigated. The lowest grain size value (81.34 nm) was found to be for CdO thin film. The Pt doped CdO films are transformed to clusters with nanoparticles. The transparency properties of the CdO thin film is changed with Pt doping. The plots of refractive index indicate abnormal and normal dispersion regions. The refractive index values of the CdO thin film are changed with Pt doping. The direct optical band gap values of the films were changed with doping of Pt. The film of 0.5% Pt doped CdO indicates the lowest optical band gap value (2.421 eV). The imaginary parts of the optical conductivity of the CdO and Pt doped CdO thin films are higher than that of the real parts of the optical conductivity.
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