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Öğe Temperature dependent electrical transport in Al/Poly(4-vinyl phenol)/ p -GaAs metal-oxide-semiconductor by sol-gel spin coating method(Hindawi, 2016-03-10) Özden, Şadan; Tozlu, Cem; Pakma, OsmanDeposition of poly(4-vinyl phenol) insulator layer is carried out by applying the spin coating technique onto p-type GaAs substrate so as to create Al/poly(4-vinyl phenol)/p-GaAs metal-oxide-semiconductor (MOS) structure. Temperature was set to 80-320 K while the current-voltage (I-V) characteristics of the structure were examined in the study. Ideality factor (n) and barrier height (φ b) values found in the experiment ranged from 3.13 and 0.616 eV (320 K) to 11.56 and 0.147 eV (80 K). Comparing the thermionic field emission theory and thermionic emission theory, the temperature dependent ideality factor behavior displayed that thermionic field emission theory is more valid than the latter. The calculated tunneling energy was 96 meV.Öğe Batman ilindeki ince film a-Si teknolojili fotovoltaik sistemin performans değerlendirmesi(Balıkesir Üniversitesi, 2018-07-17) Pakma, OsmanBu çalışmada Batman ilinde ince film a-Si teknolojisine sahip 2.16 kWp güce sahip şebeke bağlantılı sistemin bir yıllık elektrik enerjisi üretim verileri alınmış ve modüllerin performansı dış parametrelerde göz önüne alınarak değerlendirilmiştir. Sistem ölçümleri Ocak ayından Aralık ayına kadar tüm 2016 yılını kapsamaktadır. İnce film a-Si PV sistemden 2016 yılı süresince şebekeye 2.631 MWh enerji sağlanmıştır. Sistemin nihai verimi (Yf) 1.13 den 4.89 kWh/KWp/gün’e, performans oranı da (PO) %53 ile %78 arasında değişmektedir. Ortam ve buna bağlı olarak modül sıcaklıklarının sistem performansına etkisinin %6 - %9 arasında olduğu hesaplanmıştır. Ayrıca diğer sistem bölümlerinin de sistem performansı üzerinde değişen oranlarda etkili olduğu belirlenmiştir.Öğe Improvement of diode parameters in Al/n-Si schottky diodes with coronene interlayer using variation of the illumination intensity(Elsevier, 2017-12-15) Pakma, Osman; Çavdar, Şükrü; Koralay, Haluk; Tuğluoğlu, Nihat; Yüksel, Ömer FarukIn present work, Coronene thin films on Si wafer have been deposited by the spin coating method. It has been ultimately produced Al/Coronene/n-Si/In Schottky diode. Current–voltage (I-V) measurements have been used to determine the effect of illumination intensity in the Schottky diodes. The barrier height (ΦB) values increased as ideality factor (n) values decreased with a increase in illumination intensity. The ΦB values have been found to be 0.697 and 0.755 eV at dark and 100 mW/cm2, respectively. The n values have been found to be 2.81 and 2.07 at dark and 100 mW/cm2, respectively. Additionally, the series resistance (Rs) values from modified Norde method and interface state density (Nss) values using current-voltage measurements have been determined. The values of Rs have been found to be 1924 and 5094 Ω at dark and 100 mW/cm2, respectively. The values of Nss have been found to be 4.76 × 1012 and 3.15 × 1012 eV−1 cm−2 at dark and 100 mW/cm2, respectively. The diode parameters are improved by applying the variation of illumination intensity to the formed Schottky diodes.Öğe 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 Photoelectric and photocapacitance characteristics of Au/pyrene/N-Si MIS structures(Journal of Non-Oxide Glasses, 2017-04-01) Güllü, Ömer; Pakma, Osman; Özaydın, Cihat; Arsel, İsmail; Turmuş, MesutThis paper presents in-depth analysis of the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of identically prepared Au/Pyrene(C16H10)/n-Si hybrid organic-oninorganic semiconductor photovoltaic cells (total 43 diodes). The barrier heights, ideality factors and reverse bias saturation currents of all devices were extracted from the electrical characteristics. The mean barrier height, mean ideality factor and mean saturation current from I-V measurements were calculated as 0.79 ± 0.01 eV, 1.40 ± 0.08 and (1.01 ± 0.46)x10-8 A, respectively. Also, the photoelectric (I-V) and photocapacitance (C-V and conductance (G)-voltage (V)) characteristics of the Au/Pyrene/n-Si device under 100 mW/cm2 light illumination were investigated. It has been seen that the light illumination increases strongly the current, capacitance and conductance values of the device due to electron-hole charge pair generation. The C-V and G-V characteristics under illumination have shown a non-monotonic dependence of capacitance on frequency giving rise to a peak. This is attributed to the existence of electrically active traps. The open circuit voltage and short circuit current of the Au/Pyrene/n-Si device were extracted as 80 mV and 30 µA, respectively.Öğe Current mechanism in HfO 2-gated metal-oxide-semiconductor devices(Hindawi, 2012-06-19) Pakma, OsmanThe present study aimed to examine the current density-voltage (J-V) characteristics of Al/HfO2/p-Si (MOS) structure at temperatures ranging between 100 and 320 K and to determine the structure’s current transport mechanism. The HfO2 film was coated on a single side of the p-Si (111) crystal using the spin coating method. The J-V measurements of the obtained structure at the temperatures between 100 and 320 K revealed that the current transport mechanism in the structure was compatible with the Schottky emission theory. The Schottky emission theory was also used to calculate the structure’s Schottky barrier heights (φB), dielectric constants (εr) and refractive index values of the thin films at each temperature value. The dielectric constant and refractive index values were observed to decrease at decreasing temperatures. The capacitance-voltage (C-V) and conductancevoltage (G/ω-V) characteristics of Al/HfO2/p-Si (MOS) structure was measured in the temperature range of 100–320 K. The values of measured C and G/ω decrease in accumulation and depletion regions with decreasing temperature due to localized Nss at Si/HfO2 interface.Öğe Organik arayüzey tabakalı Al/CuPc /p-InP kontakların fabrikasyonu ve elektriksel parametrelerinin incelenmesi(Batman Üniversitesi, 2015-07-01) Aslan, Filiz; Güllü, Ömer; Ocak, Yusuf Selim; Rüzgar, Şerif; Tombak, Ahmet; Özaydın, Cihat; Pakma, Osman; Arsel, İsmailBu çalışmada termal buharlaştırma metodu kullanılarak bakır fitalosiyanin (CuPc) p-InP kristali üzerine kaplandı. Yine termal buharlaştırma sistemi kullanılarak oluşan ince organik film üzerine vakum ortamında alüminyum metali kaplandı ve Al/CuPc/p-InP diyot yapısı oluşturuldu. Al/CuPc/p-InP diyotunun oda sıcaklığında, karanlık ve aydınlık ortamda akım-gerilim (I-V) ölçümleri alındı. I-V grafiğinden bu yapının doğrultucu özellik gösterdiği görüldü. Aydınlık ortamda yapılan ölçümler 100 mW/cm2 ışık şiddeti altında yapıldı ve bu ölçümler doğrultusunda diyotun fotodiyot özellik gösterdiği görüldü. Ayrıca farklı yöntemlerle Al/CuPc/p-InP Schottky diyotunun karakteristik parametreleri ( idealite faktörü (n) ,engel yüksekliği (Φb) ve seri direnç (Rs) ) hesaplandı.Öğe Interface effects of annealing temperatures in Al/HfO2/p-Si (MIS) structures(Gazi Üniversitesi, 2017-09-20) Özden, Şadan; Pakma, OsmanIn this study, Al/HfO2/p-Si (MIS) structures were prepared by using the sol-gel method for three different annealing temperatures. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of these structures were investigated by taking into consideration the effect of the interfacial insulator layer and surface states (Nss) at room temperature. All of the structures showed non-ideal I-V behaviour with ideality factor (n) in the range between 2.35 and 4.42 owing to interfacial insulator layer and surface states. The values of Nss and barrier height (fb) for three samples were calculated. The values of n and Nss ascend with increasing the insulator layer thickness (δ) while the values of fb decreases.Öğe A novel device behavior of al/coronene/n-gaas/in organicbased schottky barrier diode(Jomard Publishing, 2019) Akın, Ümmühan; Yüksel, Ömer Faruk; Pakma, Osman; Koralay, Haluk; Çavdar, Şükrü; Tuğluoğlu, Nihat. A new Schottky barrier diode of Al/Coronene/n-GaAs/In was successfully prepared using spincoating method. The interface state and electrical properties of Al/Coronene/n-GaAs Schottky barrier diode have been studied by current– voltage (I–V) data in dark and light. The key diode parameters such as ideality factor, Schottky barrier height, rectification ratio, series and shunt resistances were evaluated from I–V data. The effective forward conduction mechanisms were determined as the thermionic emission at low voltage. Results obtained at room temperature (300 K) showed highly rectifying devices under dark and light. The barrier height ( B ) of the diode was obtained as 0.901 eV and 0.842 eV under dark and light, respectively. The ideality factor (n) of the diode was calculated to be 1.49 and 1.82 under dark and light, respectively. The values of series resistance ( ) Rs obtained from Cheung-Cheung technique were determined to be 18 and 16 under dark and light, respectively. The interface states density (Nss) of the Shottky device exhibits an exponential decrease with bias from 5.31x1010 eV-1 cm-2 and 7.24x1010 eV-1 cm-2 at (Ec-0.338) eV to 1.84x1010 eV-1 cm-2 and 2.17x1010 eV-1 cm-2 at (Ec-0.640) eV under dark and light, respectively.
