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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 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 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.Öğe Electrical analysis of organic interlayer based metal/interlayer/semiconductor diode structures(Journal of Applied Physics, 2009-01) Güllü, Ömer; Turut, AbdulmecitIn this work, metal/interlayer/semiconductor (MIS) diodes formed by coating of an organic film to p-Si semiconductor substrate were prepared. Metal(Al)/interlayer (phenolsulfonphthalein=PSP)/semiconductor(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 (Phi(b)) for the Al/PSP/p-Si MIS diode were obtained as 1.45 and 0.81 eV, respectively. It was seen that the Phi(b) value of 0.81 eV calculated for the Al/PSP/p-Si MIS diode was significantly larger than value of 0.50 eV of conventional Al/p-Si Schottky diodes. Modification of the interfacial potential barrier of Al/p-Si diode was achieved by using a thin interlayer of the PSP organic material. This has been attributed to the fact that the PSP organic interlayer increases the effective barrier height by influencing the space-charge region of Si. The interface-state density of the MIS diode was determined, and the interface-state density was found to vary from 3.00 x 10(13) to 2.99 x 10(12) eV(-1) cm(-2). (C) 2009 American Institute of Physics.Öğe A study of the rectifying behaviour of aniline green-based Schottky diode(Elsevier, 2010-02) Güllü, Ömer; Aydoğan, ŞakirAn Al/aniline green (AG)/Ga2Te3 device was fabricated and the current–voltage (I–V), capacitance–voltage (C–V) and capacitance–frequency (C–f) characteristics of the device have been investigated at room temperature. The values of the ideality factor, series resistance and barrier height obtained from Cheung and Norde methods were compared, and it was seen that there was an agreement with each other. It was seen that the forward bias current–voltage characteristics at sufficiently large voltages has shown the effect of the series resistance. In addition, it was seen from the C–f characteristics that the values of capacitance have been decreased towards to the high frequencies. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the Ga2Te3 that can follow the ac signal.Öğe Electrical characteristics of Co/n-Si schottky barrier diodes using I – V and C – V measurements electrical characteristics of Co/n-Si schottky barrier diodes using I – V and C – V measurements(Chinese Physics Letters, 2009-06) Güllü, Ömer; Güler, Gülşen; Karataş, Şükrü; Bakkaloğlu, Ömer FarukElectrical characteristics of Co/n-Si Schottky barrier diodes are analysed by current-voltage (I – V) and capacitance-voltage (C – V) techniques at room temperature. The electronic parameters such as ideality factor, barrier height and average series resistance are determined. The barrier height 0.76eV obtained from the C – V measurements is higher than that of the value 0.70eV obtained from the I – V measurements. The series resistance RS and the ideality factor n are determined from the d ln(I)/dV plot and are found to be 193.62Ω, and 1.34, respectively. The barrier height and the RS value are calculated from the H(I) – I plot and are found to be 0.71 eV and 205.95Ω. Furthermore, the energy distribution of the interface state density is determined from the forward bias I – V characteristics by taking into account the bias dependence of the effective barrier height. The interface state density Nss ranges from 6.484 × 1011 cm−2eV−1 in (EC – 0.446) eV to 2.801 × 1010 cm−2eV−1 in (EC – 0.631) eV, of the Co/n-Si Schottky barrier diode. The results show the presence of a thin interfacial layer between the metal and the semiconductor.Öğe Silicon MIS diodes with Cr2O3 nanofilm Optical morphological structural and electronic transport properties(Elsevier, 2010-04-15) Güllü, Ömer; Erdoğan, İbrahim YasinIn this work we report the optical, morphological and structural characterization and diode application of Cr2O3 nanofilms grown on p-Si substrates by spin coating and annealing process. X-ray diffraction (XRD), non-contact mode atomic force microscopy (NC-AFM), ultraviolet–visible (UV–vis) spectroscopy and photoluminescence (PL) spectroscopy were used for characterization of nanofilms. For Cr2O3 nanofilms, the average particle size determined from XRD and NC-AFM measurements was approximately 70 nm. Structure analyses of nanofilms demonstrate that the single phase Cr2O3 on silicon substrate is of high a crystalline structure with a dominant in hexagonal (1 1 0) orientation. The morphologic analysis of the films indicates that the films formed from hexagonal nanoparticles are with low roughness and uniform. UV–vis absorption measurements indicate that the band gap of the Cr2O3 film is 3.08 eV. The PL measurement shows that the Cr2O3 nanofilm has a strong and narrow ultraviolet emission, which facilitates potential applications in future photoelectric nanodevices. Au/Cr2O3/p-Si metal/interlayer/semiconductor (MIS) diodes were fabricated for investigation of the electronic properties such as current–voltage and capacitance–voltage. Ideality factor and barrier height for Au//Cr2O3/p-Si diode were calculated as 2.15 eV and 0.74 eV, respectively. Also, interfacial state properties of the MIS diode were determined. The interface-state density of the MIS diode was found to vary from 2.90 × 1013 eV−1 cm−2 to 8.45 × 1012 eV−1 cm−2.Öğe Analysis of the series resistance and interface state densities in metal semiconductor structures(Journal of Physics: Conference Series, 2009-03) Güllü, Ömer; Karataş, Şükrü; Güler, Gülşen; Bakkaloğlu, Ömer FarukThe electrical properties of Co/n-Si metal-semiconductor (MS) Schottky structure investigated at room temperature using current-voltage (I-V) characteristics. The characteristic parameters of the structure such as barrier height, ideality factor and series resistance have been determined from the I-V measurements. The values of barrier height obtained from Norde’s function were compared with those from Cheung functions, and it was seen that there was a good agreement between barrier heights from both methods. The series resistance values calculated with Cheung’s two methods were compared and seen that there was an agreement with each other. However, the values of series resistance obtained from Cheung functions and Norde’s functions are not agreeing with each other. Because, Cheung functions are only applied to the non-linear region (high voltage region) of the forward bias I–V characteristics. Furthermore, the energy distribution of interface state density was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. The results show that the presence of thin interfacial layer between the metal and semiconductorÖğe Electrical characterization of the Al/new fuchsin/n-Si organic-modified device(Elsevier, 2010-03) Güllü, Ömer; Asubay, Sezai; Turut, Abdulmecit; Aydoğan, ŞakirThe current–voltage (I–V) and the capacitance–voltage (C–V) characteristics of the Al/new fuchsin (NF)/n-Si device have been investigated at room temperature. The I–V characteristic of the device shows a good rectification. The ideality factor and the barrier height from the I–V characteristics have been determined as 3.14 and 0.80 eV, respectively. A modified Norde's function combined with the conventional I–V method has been used to extract the parameters including the barrier height and the series resistance. The barrier height and the series resistance obtained from Norde's function have been compared with those from Cheung functions, and it has been seen that there was a good agreement between those from both method. It has also been seen that the values of diode capacitance increased up to the constant values for the forward bias.
