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Öğe Design of PV energy system in Batman Turkey(AIP Conf.Proc., 2017) Pakma, Nilay; Pakma, Osman; Güllü, ÖmerÖğe Control of barrier heigth ofmetal/semiconductor contacts bymolecular organic film(2011-06) Güllü, Ömer; Turut, Abdulmecit; Kılıçoğlu, Tahsin; Özerden, EniseÖğe Electronic properties of the Al/Orange G/n-Si junction(2017-04) Güllü, Ömer; Arsel, İsmailÖğe 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.Öğe 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 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 Organometalik mangan kompleks ince filminin bazı optik özellikleri ve fotovoltaik diyot uygulaması(Ubek Yayınevi, 2019-11) Güllü, Ömer; Özaydın, Cihat; Özaydın, Mizgin TutşiÖğe 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 Pyronine-B Organik İnce Filminin Optik Özellikleri Ve Al/Pyronine-B/P-Inp Yapıların Elektronik Parametrelerinin Hesaplanması(Ubek Yayınevi, 2019-11) Güllü, Ömer; Özaydın, CihatÖğe 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.
