Browsing by Author "Gurbulak, B."

Now showing 1 - 5 of 5

Calculation of Characteristics Parameters of Au/Methyl Green/N-Si Diodes from the Current-Voltage Measurements
(Elsevier Sci Ltd, 2021) Kaya, F. S.; Duman, S.; Baris, O.; Gurbulak, B.
In this study, methyl-green (MG) organic dye layer was formed on the front side of a n-Si semiconductor via low-cost drop coating method and twenty (20) Au/MG/n-Si/Ag diodes have been identically fabricated. The fundamental diode parameters such as barrier height (BH, null b thorn , ideality factor (IF, n) and series resistance (R-s) were determined from the current-voltage (I-V) measurements by using ln(I)-V characteristics, Cheung's functions and modified Norde's functions at room temperature. The values of BH and IF calculated from ln(I)-V were varied from 0.744 to 0.862 eV and from 1.10 to 1.64 for the 20 Au/MG/n-Si/Ag diodes, respectively. The experimental BH and IF distributions calculated from the ln(I)-V characteristics and Cheung's functions were fitted by a Gaussian distribution function. The statistical analysis yielded a mean IF value of 1.26 with standard deviation (sigma) of 0.173 and a mean BH value of 0.817 eV with sigma of 0.031 eV from the ln (I)-V characteristics, respectively. It was seen that there is an agreement between the BH values calculated from ln(I)-V and other two methods. The Rs obtained from Norde's function were compared with those from Cheung's functions.
Electrical Properties of Al/P-Ge and Al/Methyl Green/P-Ge Diodes
(Taylor & Francis Ltd, 2015) Duman, S.; Turgut, G.; Ozcelik, F. S.; Gurbulak, B.
Methyl green (MG) film has been grown for the first time on p-Ge semiconductor using a simple and low-cost drop coating method. The current-voltage (I-V) characteristics of Al/p-Ge and Al/MG/p-Ge diodes have been investigated in the temperature range of 20-300K. A potential barrier height as high as 0.82eV has been achieved for Al/MG/p-Ge diode, which has high rectification rate, at room temperature. It is seen that the barrier height of the Al/MG/p-Ge diode at the room temperature is larger than that of Al/p-Ge diode and ideality factor value of 1.14 calculated for Al/MG/p-Ge diode is lower than Al/p-Ge diode. The temperature coefficient of barrier height of the Al/MG/p-Ge diode has been calculated as 2.6meV/K. The evaluation of current-voltage characteristics shows that the barrier height of the diode increases with the increasing temperature.
The Influence of Chemical Reactivity of Surface Defects on Ambient-Stable InSe-Based Nanodevices
(Royal Soc Chemistry, 2016) Politano, A.; Chiarello, G.; Samnakay, R.; Liu, G.; Gurbulak, B.; Duman, S.; Boukhvalov, D. W.
We demonstrate that, in contrast to most two-dimensional materials, ultrathin flakes of InSe are stable under ambient conditions. Despite their ambient stability, InSe-based nanodevices show an environmental p-type doping, suppressed by capping InSe with hexagonal boron nitride. By means of transport experiments, density functional theory and vibrational spectroscopy, we attribute the p-type doping assumed by uncapped InSe under an ambient atmosphere to the decomposition of water at Se vacancies. We have estimated the site-dependent adsorption energy of O-2, N-2, H2O, CO and CO2 on InSe. A stable adsorption is found only for the case of H2O, with a charge transfer of only 0.01 electrons per water molecule.
Lutetium Incorporation Influence on ZnO Thin Films Coated via a Sol-Gel Route: Spin Coating Technique
(Springer, 2016) Turgut, G.; Duman, S.; Ozcelik, F. S.; Gurbulak, B.; Dogan, S.
Pure and lutetium (Lu) incorporated zinc oxide (ZnO) thin films were deposited by a sol-gel route. The effect of Lu contribution on the properties of ZnO was examined in detail by means of XRD, AFM, SEM, UV-Vis spectrophotometer, and I-V measurements. The nano-sized ZnO:Lu samples had hexagonal wurtzite structure with c-axis (002) preferential orientation. The pure ZnO nano-particles homogeneously scattered on the film surface and this homogeneous particle distribution was deteriorated with Lu incorporation. Ohmic contacts to the ZnO:Lu films were formed using gold (Au) metallization schemes. As-deposited Au contacts exhibited linear current-voltage characteristics. The optical band gap for pure ZnO went up from 3.281 to 3.303 eV with low Lu contribution level up to 3 at.%, then it decreased with more Lu level. The Urbach energy was also studied and it was found that E-u depended on Lu incorporation level.
Silicon-Doping Influence on the Crystalline, Surface and Optical Features of Cadmium Oxide Films Deposited by Sol-Gel Spin Route
(Elsevier GmbH, 2018) Turgut, G.; Kurt, M. S.; Ertugrul, M.; Iskenderoglu, D.; Duman, S.; Gurbulak, B.
This is the first study on Si-contributed CdO films fabricated via sol-gel process. Si-doping impact on the crystalline, topographic and optical qualities of cadmium oxide has been searched with XRD, SEM, AFM and UV/vis spectrophotometer. The whole films were polycrystalline with (111) preferential direction and the crystalline degree of CdO depended on Si-contribution effect. The crystallite size of undoped-CdO incessantly decreased with Si-content, however dislocation density increased with Si-level. The spherical CdO granules were nanoscale and their sizes varied between 20-170 nm. The RMS roughness values of films changed between 5.84 nm-40.5 nm. The optical gap value of undoped-CdO continuously declined from 2.59 eV to 2.39 eV with increasing Si-content, while the Urbach energy increased from 350 meV to 468 meV with Si-level. These results reveal that the level of Si-doping affect the features of cadmium oxide. (C) 2018 Elsevier GmbH. All rights reserved.