31 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 10 / 31
Öğe N-type InP Schottky diodes with organic thin layer: Electrical and interfacial properties(Journal of Vacuum Science & Technology B, 2010-03) Güllü, Ömer; Turut, AbdulmecitThe rectifying junction characteristics of methyl red (MR) organic film on n-type InP substrate have been studied. It has been observed that MR-based structure shows an excellent rectifying behavior and that the MR film increases the effective barrier height by influencing the space charge region of the n-type InP. The barrier height and ideality factor values for this structure have been obtained as 0.75 eV and 1.93 from the forward bias current-voltage characteristics, respectively. By using capacitance-voltage characteristics at 1 MHz, the barrier height and the carrier concentration values have been calculated as 0.93 eV and 5.13×1015 cm−3, respectively. The energy distributions of the interface states and their relaxation times have been determined from the forward bias capacitance-frequency and conductance-frequency characteristics. Moreover, it was seen that both the interface-state density and the relaxation time of the interface states decreased with bias voltage from experimental results.Öğe Fabrication and electrical characterization of ZnO SiO2 p Si structure with outsized diode factor(European Union, 2010) Kavasoğlu, Neşe; Kavasoğlu, Abdülkadir Sertap; Pakma, Osman; Kabakçı, Murat; Birgi, Özcan; Oktik, ŞenerÖğe Control of barrier heigth ofmetal/semiconductor contacts bymolecular organic film(2011-06) Güllü, Ömer; Turut, Abdulmecit; Kılıçoğlu, Tahsin; Özerden, EniseÖğe 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 Radiation dose estimation and mass attenuation coefficients ofcement samples used in Turkey(Elsevier, 2009-12-16) Damla, Nevzat; Çevik, Uğur; Kobya, Ali İhsan; Çelik, Ahmet; Çelik, Necati; Grieken, R. VanDifferent cement samples commonly used in building construction in Turkey have been analyzed for natural radioactivity using gamma-ray spectrometry. The mean activity concentrations observed in the cement samples were 52, 40 and 324 Bq kg−1 for 226Ra, 232Th and 40K, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries and world average limits. The radiological hazard parameters such as radium equivalent activities (Raeq), gamma index (Iγ) and alpha index (Iα) indices as well as terrestrial absorbed dose and annual effective dose rate were calculated and compared with the international data. The Raeq values of cement are lower than the limit of 370 Bq kg−1, equivalent to a gamma dose of 1.5 mSv y−1. Moreover, the mass attenuation coefficients were determined experimentally and calculated theoretically using XCOM in some cement samples. Also, chemical compositions analyses of the cement samples were investigated.Öğe On The Profile Of Frequency Dependent Series Resistance And Interface States In Al/TiO2/p-Si (MIS) Structures(Batman Üniversitesi, 2012) Arsel, İsmailSol-gel yöntemiyle hazırlanan Al/TiO2/p-Si (MIS) yapıların iletkenlik-voltaj(G/ω-V) ve kapasitans-voltaj (C-V) karakteristiklerinin frekansa bağımlılığı oda sıcaklığında seri dirençler (Rs) ve arayüzey (Nss) durumlarına etkisi gözönüne alınarak incelenmiştir. Ölçülen kapasidans (C) ve iletkenkiğin (G/ω), frekansa ve öngerilime kuvvetle bağlı olduğu bulunmuştur. Ölçülen sığa (C) ve iletkenlik (G/ω) değerlerinin, dolma ve boşalma bölgelerinde frekansın artması ile azaldığı, Si/TiO2 arayüzeyinde Nss ölçülmüştür. Seri direnç-gerilim ( Rs-V), grafiğinde bir tepe noktası vardır ve tepe noktasının yeri, azalan frekansla birlikte ters bölgeye doğru kayar. Gerçek (MIS) kapasidans (C) ve iletkenlik (G/ω) değerlerini elde etmek amacıyla kapasidans-gerilim (C-V) ve iletkenlik-gerilim (G/ω-V) ölçümlerinin her ikisi ileri ve geri önyargılar altında seri dirençlerin etkisi için düzeltilmiştir. Frekansa bağlı kapasidans-gerilim (C-V) ve iletkenlik-gerilim (G/ω-V) ölçümleri son derece etkili elektriksel karakteristiklerin çok önemli iki parametresi MMS yapısında Rs ve Nss olduğunu gösterir.Öğe Electrical analysis of organic dye based MIS Schottky contacts(Microelectronic Engineering, 2010-05-25) Güllü, Ömer; Turut, AbdulmecitIn this work, we prepared metal/interlayer/semiconductor (MIS) diodes by coating of an organic film onp-Si substrate. Metal(Al)/interlayer(Orange G@OG)/semiconductor(p-Si) MIS structure had a good recti-fying behavior. By using the forward-biasI–Vcharacteristics, the values of ideality factor (n) and barrierheight (BH) for the Al/OG/p-Si MIS diode were obtained as 1.73 and 0.77 eV, respectively. It was seen thatthe BH value of 0.77 eV calculated for the Al/OG/p-Si MIS diode was significantly larger than the value of0.50 eV of conventional Al/p-Si Schottky diodes. Modification of the potential barrier of Al/p-Si diode wasachieved by using thin interlayer of the OG organic material. This was attributed to the fact that the OGorganic interlayer increased the effective barrier height by influencing the space charge region of Si. Theinterface-state density of the MIS diode was found to vary from 2.79x1013to 5.80x1012eVx1cmx2.Öğe Electronic properties of the metal organic interlayer inorganic semiconductor sandwich device(Elsevier, 2010-03) Güllü, Ömer; Turut, Abdulmecit; Kılıçoğlu, TahsinIn this study, we prepared a Metal(Al)/Organic Interlayer(Congo Red=CR)/Inorganic Semiconductor (p-Si) (MIS) Schottky device formed by coating of an organic film on p-Si semiconductor wafer. The Al/CR/p-Si MIS device had a good rectifying behavior. By using the forward bias I–V characteristics, the values of ideality factor (n) and barrier height (Φb) for the Al/CR/p-Si MIS device were obtained as 1.68 and 0.77 eV, respectively. It was seen that the Φb value of 0.77 eV calculated for the Al/CR/p-Si MIS device was significantly higher than value of 0.50 eV of the conventional Al/p-Si Schottky diodes. Modification of the interfacial potential barrier of the Al/p-Si diode was achieved by using a thin interlayer of the CR organic material. This was attributed to the fact that the CR organic interlayer increased the effective barrier height by influencing the space charge region of Si. The interface-state density of the MIS diode was found to vary from 1.24×1013 to 2.44×1012 eV−1 cm−2.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 Electrical properties of organic–ınorganic semiconductor device based on rhodamine-101(SpringerLink, 2009-05) Güllü, Ömer; Turut, Abdulmecit; Yıldırım, Nezir; Çakar, MuzafferRhodamine-101 (Rh101) thin films on n-type Si substrates have been formed by means of evaporation, thus Sn/Rh101/n-Si heterojunctions have been fabricated. The Sn/Rh101/n-Si devices are rectifying. The optical energy gaps have been determined from the absorption spectra in the wavelength range of 400 nm to 700 nm. Rh101 has been characterized by direct optical absorption with an optical edge at 2.05 ± 0.05 eV and by indirect optical absorption with␣an optical edge at 1.80 ± 0.05 eV. It was demonstrated that trap-charge-limited current is the dominant transport mechanism at large forward bias. A␣mobility value of μ = 7.31 × 10−6 cm2 V−1 s−1 for Rh101 has been obtained from the forward-bias current–voltage characteristics.
