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Öğe The Current voltage and Capacitance voltage frequency characteristics of the Al methyl violet n Si diode(Türk Fizik Derneği, 2016-09) Güllü, Ömer; Arsel, İsmailÖğe Electrical characteristics of the Al/Congo Red (CR)/p-Si semiconductor diodes(Dumlupınar Üniversitesi, 2015-05) Güllü, Ömer; Pakma, Osman; Turut, Abdulmecit; Arsel, İsmailIn this work, we have studied the electrical characteristics of the Al/CR/p-Si MIS Schottky structures formed by coating of the organic material directly on p-Si substrate. It has been seen that the CR thin film on the p-Si substrate has indicated a good rectifying behavior. The barrier height and the ideality factor of the device have been calculated from the I-V characteristic. We have also studied the suitability and possibility of the MIS diodes for use in barrier modification of Si MS diodes. In addition, we have compared the parameters of the Al/CR/p-Si MIS Schottky diodes with those of conventional Al/p-Si MS diodes. We have observed that the b value of 0.77 eV obtained for the Al/CR/p-Si device was significantly larger than BH value of the conventional Al/p-Si MS contact. Thus, the modification of the interfacial potential barrier for metal/Si diodes has been achieved by using the CR organic interlayer. This was attributed to the fact that the CR interlayer increased the effective b by influencing the space charge region of Si. The interface-state density of the MIS diode was found to vary from 1.24×1013 eV-1 cm-2 to 2.44×1012 eV-1 cm-2.Öğe Current-voltage, capacitance-voltage-frequency and ınterface characteristics ofmetal/organic dye molecule/P-Type Inp photovoltaic device(2011-09) Güllü, Ömer; Özerden, Enise; Kılıçoğlu, Tahsin; Turut, AbdulmecitÖğe The electronic properties of the Al new fuchsin n Si Schottky Structures(Türk Fizik Derneği, 2016-09) Güllü, Ömer; Özkan, SametÖğe Current-capacitance-voltage characteristics of the Al/methyl red/n-InP diode(2017-04) Güllü, Ömer; Arsel, İsmailÖğe Electronic properties of the Al/Orange G/n-Si junction(2017-04) Güllü, Ömer; Arsel, İsmailÖğe Control of barrier heigth ofmetal/semiconductor contacts bymolecular organic film(2011-06) Güllü, Ömer; Turut, Abdulmecit; Kılıçoğlu, Tahsin; Özerden, EniseÖğe Statistical analysis of solar radiation models onto inclined planes for climatic conditions of Batman (Turkey)(İstanbul University, 2015) Derse, Mehmet Sait; Öztürker, Hakkı; Pakma, Nilay; Pakma, Osman; Güllü, Ömer; Arsel, İsmailSolar energy is one of the most widely used renewable energy resources in the world. A drawback, common to the photovoltaic systems (PV) is their unpredictable nature and their output cannot be accurately predicted, because, these systems are dependent on climatic conditions. Solar radiation data are the best source of information for proper design of PV systems. In this study; hourly tilted surface solar radiation is measured at different slope angles in Batman (Turkey). Selected models were compared on the basis of the statistical error tests; mean square errors (MSE), mean absolute errors (MAE) and root mean square errors (RMSE) and mean absolute percentage error (MAPE). Besides, a new equation was developed to calculate monthly average daily global solar radiation in Batman.Öğe Electrical parameters of safranine T N silicon contacts(İstanbul University, 2015) Güllü, Ömer; Arsel, İsmail; Özkan, Samet; Özaydın, Cihat; Pakma, Osman; Turut, AbdülmecitIn this work, it has been investigated current-voltage (I-V) andcapacitance-voltage-frequency (C-V-f) characteristics of the Al/SafranineT(ST)/n-Si structure. The values of the ideality factor, series resistance and barrier height calculated by using different methods were compared. It was seen that there was an agreement with each other. Also, it was seen that the barrier height value for our device was higher than one value of 0.50 eV of conventional Al/n-Si Schottky contact. The change in the barrier height value of the device was ascribed to ST thin layer modifying the effective barrier height by influencing the space charge region of the Si inorganic semiconductor. The downward concave curvature of the forward bias current-voltage characteristics at sufficiently large voltages have been attributed to the effect of series resistance. Thus, the concavity of the forward bias current-voltage characteristics increases with increasing series resistance value. It has been seen that the values of capacitance are almost independent to a certain value of frequency, after this value, the capacitance decreases with increasing frequency. The higher values of capacitance at low frequencies have been attributed to the excess capacitance resulting from the interface states in equilibrium with the n-Silicon that could follow the alternating current signal.Öğe I V and C V F characteristics of aniline green N type silicon diode(İstanbul University, 2015) Özkan, Samet; Güllü, Ömer; Arsel, İsmail; Özaydın, Cihat; Pakma, Osman; Turut, AbdülmecitWe have studied the I-V, C-V and C-f characteristics of the Aniline Green (AG)/n-type Si structure. In organic/inorganic semiconductor contact applications, in order to keep the technological difficulties and unknowns to a minimum, silicon is generally chosen as the substrate semiconducting material. In this structure, deposition of organic materials on the inorganic semiconductor can generate large number of interface states at the semiconductor surface that strongly influence the electrical properties of the AG/n-Si structure. The values of the ideality factor, series resistance and barrier height obtained from two methods were compared, and it was seen that there was an agreement with each other. The downward concave curvature of the forward bias current-voltage characteristics at sufficiently large voltages is caused by the presence of the effect of series resistance. Thus, the concavity of the forward bias current-voltage characteristics increases with the increasing series resistance value. The high resistance values have given the high ideality factors. Also, the higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the nSi that can follow the ac signal.Öğe Performance analysis of different PV modules technologies for Batman (Turkey)(İstanbul University, 2015) Pakma, Osman; Öztürker, Hakkı; Derse, Mehmet Sait; Pakma, Nilay; Güllü, ÖmerThe performance of a photovoltaic (PV) system depends on both the module technology and also on the outdoor conditions. The impact of solar radiation, ambient and module temperature, humidity, dust and ventilation can strongly affect energy production of the PV system. In this study, three 2.2 kW grid-connected PV generation systems under the outdoor conditions are analyzed in Batman (Turkey). The types of modules examined in this study are: monocrystalline silicon, polycrystalline silicon and amorphous silicon. The monthly and annual performance ratios have been calculated for the three modules and a comparison is presented here. Optimization potentials of Batman are also discussed.Öğe Structural and optical investigations on ZrO2 thin films prepared by wet chemical synthesis method(İstanbul University, 2015) Özdemir, Cengiz; Pakma, Osman; Kari̇per, İshak Afşin; Özaydın, Cihat; Güllü, ÖmerThe aim of the study is to develop a more economic and easier method which has lower temperature in obtaining ZrO2 thin films contrary to the literature. In this study, we produced thin ZrO2 films on amorphous glass substrates through the wet chemical method by using different chemicals with the same starting reactive. X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible (UV-VIS) spectroscopy measurements of the produced films were conducted and the results were compared. The best method has been identified at the end of the analysis and it has been observed that the features of the films produced with this method have given better results than both the films produced by using different reagents and the films produced in literature.Öğe Current transport mechanism of Cu In1 x Gax S1 y sey 2 based heterojunction solar cells(İstanbul University, 2015) Pakma, Osman; Eriş, FerhatIn this study; temperature-dependent current-voltage measurements are used to determine the dominant currenttransport mechanism of ZnO/CdS/Cu(In,Ga)(S,Se)2 heterojunction solar cells. The dominant current-transport mechanism is mainly driven by changes in the Cu and S-stoichiometry. Whereas Cu and S rich devices are dominated by recombination at the CdS/absorber interface, bulk recombination in Cu and S poor devices irrespective of the band gab energy of the absorber.Öğe Photoelectrical characteristics of Al/Coronone/n-Si schottky photodiode(Selçuk Üniversitesi, 2017) Tuğluoğlu, Nihat; Yüksel, Ömer Faruk; Pakma, OsmanÖğe I V characteristics of the orange G P type silicon contacts(Dumlupınar Üniversitesi, 2015) Güllü, Ömer; Arsel, İsmail; Pakma, Osman; Özaydın, Cihat; Turut, AbdülmecitÖğe Characterization of Au N Inp photovoltaic structure with organic thin film(Uppsala University, 2012) Güllü, Ömer; Özerden, Enise; Rüzgar, Şerif; Asubay, Sezai; Pakma, Osman; Kılıçoğlu, Tahsin; Türüt, AbdulmecitÖğe Design of PV energy system in Batman Turkey(AIP Conf.Proc., 2017) Pakma, Nilay; Pakma, Osman; Güllü, ÖmerÖğe Optical properties of iron xanthate thin film on different substrates(AIP Conf.Proc., 2017) Pakma, Osman; Kari̇per, İshak Afşin; Özposan, TalatÖğe The effects of high-energy electron irradiation on the electrical characteristics of a lead/rhodamine-101/p-Si diode(Çukurova Üniversitesi, 2017) Güllü, Ömer; Pakma, OsmanHigh-energy radiation penetrates the metal-semiconductor (MS) interface and causes damage deep below the interface. Low-energy radiation causes severe lattice damage in the form of vacancies, interstitials and defect complexes at the near interface of the device. The one kind of the radiation is electron beam which is accelerated. Mills was the first to recognize that electrons with energy of 1 MeV would possess enough energy to displace an atom from its lattice position. This observation has led to the increased use of electron accelerators in radiation damage studies. This use has been motivated by two important facts. First, electron bombardment experiments permit the determination of the energy required to remove an atom from its initial position. This is done by increasing the energy of the electrons until an observable change in a radiation-sensitive property is seen. The second important basis for the use electrons lie in the fact that as long as the energy of the electrons is close to the displacement threshold, it is presumed, that only single Frenkel pairs are formed. Thus, many radiation-induced phenomena can be analyzed in terms of a single vacancy and/or interstitial atom, and one avoids the complication attendant upon the generation of complex damage regions presumed to occur in heavy-charged particle irradiation. In the present paper, a lead/rhodamine-101(Rh101)/p-Si metal/organic interlayer/ semi-conductor diode was fabricated and the effect of 6 MeV-electron irradiation on the electrical characteristics of the diode structure was investigated. It was seen that after electron irradiation the barrier height values, the series resistance values and ideality factors increased. Furthermore, it was seen that the capacitance values increased after electron irradiation. This was attributed to the change in dielectric constant at the interface and/or to decrease in the net ionized dopant concentration and the interface states. The degradation of the diode properties may be due to the introduction of electron irradiationinduced interfacial defects via displacement damage.Öğe Some electrical parameters of the Sn/p-Si diode under γ-irradiation(Çukurova Üniversitesi, 2017) Pakma, Osman; Güllü, ÖmerThe radiation response of metal-semiconductor (MS) contacts has been found to alter significantly when the structures are exposed to pre-irradiation processes at determined doses. Radiation doses greater than a kilogray exposure may cause strong changes on the electrical characteristics of MS structures. It has been also shown that the particle or gamma irradiations induce defects in the band gap which affects the free carrier concentration and leads to an increase and decrease of barrier height in p-type and n-type semiconductors, respectively. The knowledge of the influence of radiation damage on the Schottky barrier diodes (SBDs) performance is a fundamental field of research, having technological relevance for many applications in the semiconductor electronic devices. Hence, it is very much essential to evaluate the effect of irradiation and identify the degradation mechanism to understand the failure mechanisms. In this work, we have investigated the electrical parameters of the Sn/p-Si Schottky barrier diodes by using I-V and C-V characteristics under γ-irradiation at room temperature. The basic diode parameters such as ideality factor, barrier height, series resistance and reverse saturation current were extracted from electrical measurements as a function of the irradiation dose. The results indicated that γ-irradiation induced an increase in the effective Schottky barrier height extracted from both I-V and C-V measurements. Also, it was seen that ideality factor increased with the increasing γ-irradiation doses. We have also observed that the reverse bias current of the Sn/Si contact exceedingly decreased with increasing irradiation dose with low energy (60 keV). The basic results as related to the gamma irradiation have been indicated that this device may have applications as radiation sensors in order to detect the low energy gamma radiation.
