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Öğe Wet chemical methods for producing mixing crystalline phase ZrO 2 thin film(Elsevier, 2016-07) Pakma, Osman; Özdemir, Cengiz; Kariper, İshak Afşin; Özaydın, Cihat; Güllü, ÖmerThe aim of the study is to develop a more economical and easier method for obtaining ZrO 2 thin films at lower temperature, unlike the ones mentioned in the literature. For this purpose, wet chemical synthesis methods have been tested and XRD, UV-VIS and SEM analysis of ZrO 2 thin films have been performed. At the end of the analysis, we identified the best method and it has been found that the features of the films produced with this method were better than the films produced by using different reagents, as well as the films reported in the literature. Especially it has been observed that the transmittance of the film produced with this method were higher and better than the films in the literature and the others. In addition, refractive index of the film produced with this method was observed to be lower. Moreover, by using the same method Al/ZrO 2 /p-Si structure has been obtained and it has been compared with Al/p-Si reference structure in terms of electrical parameters.Öğe Current density-voltage analyses and interface characterization in Ag/DNA/p-InP structures(American Institute of Physics, 2012-02-15) Güllü, Ömer; Pakma, Osman; Türüt, AbdülmecitThe current density-voltage (J-V) characteristics of Ag/DNA/p-InP metal-insulator-semiconductor (MIS) structures have been investigated in room temperature. We have observed that the Ag/DNA/p-InP structure shows an excellent rectifying behavior and that this structure increases the barrier height (φ b0). The main electrical parameters of these structures, such as ideality factor (n), barrier height, and average series resistance values were found to be 1.087, 0.726 eV, and 66.92Ω. This value of n was attributed to the presence of an interfacial insulator layer at the Ag/p-InP interface and the density of interface states (N ss) localized at the InP/DNA interface. The values of N ss localized at the InP/DNA interface were found at 0.675-E v in the 1.38 × 10 12 eV -1 cm -2.Öğe Analysis of electrical and photoelectrical properties of ZnO/p-InP heterojunction(Elsevier, 2011-06) Ocak, Yusuf Selim; Kulakçı, Mustafa; Turan, Raşit; Kılıçoğlu, Tahsin; Güllü, ÖmerA ZnO/p-InP heterojunction has been fabricated by dc sputtering of ZnO on p-InP. It has been observed that the device has a good rectification. The electrical properties of the device such as ideality factor, barrier height, series resistance have been calculated using its current-voltage (I-V) measurements between 300 and 380 K with 20 K intervals. The short current density (Jsc) and open circuit voltage (Voc) parameters have been determined between 40 and 100 mW/cm2. The photovoltaic parameters of the device have been also determined under 100 mW/cm2 and AM1.5 illumination condition.Öğe Characterization of an Au/n-Si photovoltaic structure with an organic thin film(Elsevier, 2013-08) Özaydın, Cihat; Akkılıç, Kemal; İlhan, Salih; Rüzgar, Şerif; Güllü, Ömer; Temel, HamdiWe demonstrate that a copper(II) organic complex can control the electrical characteristics of conventional Au/n-Si metal-semiconductor (MS) contacts. We investigated the electronic and photovoltaic properties of a Cu(II) complex/n-Si heterojunction diode. The ideality factor n and barrier height Φb of the diode were 2.22 and 0.736 eV, respectively. An ideality factor greater than unity indicates that the diode exhibits non-ideal current-voltage behavior. This behavior results from the effect of series resistance and the presence of an interfacial layer. The series resistance and barrier height determined using Norde's method were 6.7 kΩ and 0.77 eV, respectively. The device showed photovoltaic behavior, with a maximum open-circuit voltage of 0.24 V and a short circuit current of 1.7 μA under light of 8 mW/cm2.Öğe Electronic properties of Al/DNA/p-Si MIS diode: Application as temperature sensor(Elsevier, 2011-01) Güllü, Ömer; Türüt, AbdülmecitThe current-voltage (I-V) measurements were performed in the temperature range (200-300 K) on Al/DNA/p-Si Schottky barrier type diodes. The Schottky diode shows non-ideal I-V behaviour with ideality factors n equal to 1.34 ± 0.02 and 1.70 ± 0.02 at 300 K and 200 K, respectively, and is thought to have a metal-interface layer-semiconductor (MIS) configuration. The zero-bias barrier height Φb determined from the I-V measurements was 0.75 ± 0.01 eV at 300 K and decreases to 0.61 ± 0.01 eV at 200 K. The forward voltage-temperature (VF-T) characteristics were obtained from the I-V measurements in the temperature range 200-300 K at different activation currents (IF) in the range 20 nA-6 μA. The VF-T characteristics were linear for three activation currents in the diode. From the VF-T characteristics at 20 nA, 100 nA and 6 μA, the values of the temperature coefficients of the forward bias voltage (dV F/dT) for the diode were determined as -2.30 mV K-1, -2.60 mV K-1 and -3.26 mV K-1 with a standard error of 0.05 mV K-1, respectively.
