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Öğe The characteristic diode parameters in Ti/p-InP contacts prepared by DC sputtering and evaporation processes over a wide measurement temperature(World Scientific, 2017-06) Ejderha, Kadir; Asubay, Sezai; Yıldırım, Nezir; Güllü, Ömer; Türüt, Abdülmecit; Abay, BahattinThe titanium/p-indium phosphide (Ti/p-InP) Schottky diodes (SDs) have been prepared by thermal evaporation and DC magnetron sputtering deposition. Then, their current-voltage (I-V) characteristics have been measured in the sample temperature range of 100-400K with steps of 20K. The characteristic parameters of both Ti/p-InP SDs have been compared with each other. The barrier height (BH) values of 0.824 and 0.847 at 300K have been obtained for the sputtered and the evaporated SDs, respectively. This low BH value for the sputtered SD has been attributed to some defects introduced by the sputtered deposition technique over a limited depth in to the p-type substrate. The BH of the evaporated and sputtered diodes has decreased with the standard deviations of 58 and 64mV obeying to double-Gaussian distribution (GD) in 220-400K range, respectively, and it has seen a more sharper reduction for the BHs with the standard deviations of 93 and 106 mV in 100-220K range. The Richardson constant values of 89.72 and 53.24A(Kcm)-2 (in 220-400K range) for the evaporated and sputtered samples, respectively, were calculated from the modified ln(I0/T2)-q2σs2/2k2T2 vs (kT)-1 curves by GD of the BHs. The value 53.24A(Kcm)-2 for the sputtered sample in high temperatures range is almost the same as the known Richardson constant value of 60A(Kcm)-2 for p-type InP.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 Electronic parameters of high barrier Au/Rhodamine-101/n-Inp Schottky diode with organic interlayer(Elsevier, 2012-01) Güllü, Ömer; Aydoğan, Şakir; Türüt, AbdülmecitIn this work, we present that Rhodamine-101 (Rh-101) organic molecules can control the electrical characteristics of conventional Au/n-InP metal-semiconductor contacts. An Au/n-InP Schottky junction with Rh-101 interlayer has been formed by using a simple cast process. A potential barrier height as high as 0.88 eV has been achieved for Au/Rh-101/n-InP Schottky diodes, which have good current-voltage (I-V) characteristics. This good performance is attributed to the effect of formation of interfacial organic thin layer between Au and n-InP. By using capacitance-voltage measurement of the Au/Rh-101/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as 0.78 V and 0.88 eV, respectively. From the I-V measurement of the diode under illumination, short circuit current and open circuit voltage have been extracted as 1.70 μA and 240 mV, respectively.Öğe Electronic parameters of MIS Schottky diodes with DNA biopolymer interlayer(Walter de Gruyter, 2015-09-01) Güllü, Ömer; Türüt, AbdülmecitIn this work, we prepared an ideal Cu/DNA/n-InP biopolymer-inorganic Schottky sandwich device formed by coating a n-InP semiconductor wafer with a biopolymer DNA. The Cu/DNA/n-InP contact showed a good rectifying behavior. The ideality factor value of 1.08 and the barrier height (Φb) value of 0.70 eV for the Cu/DNA/n-InP device were determined from the forward ias I-V characteristics. It was seen that the Φb value of 0.70 eV obtained for the Cu/DNA/n-InP contact was significantly larger tan the value of 0.48 eV of conventional Cu/n-InP Schottky diodes. Modification of the interfacial potential barrier of Cu/n-InP iode was achieved using a thin interlayer of DNA biopolymer. This was attributed to the fact that DNA biopolymer interlayer increased the effective barrier height by influencing the space charge region of InP.Öğe Electronic properties of Al/DNA/p-Si MIS diode: Application as temperature sensor(Elsevier, 2011-01) Güllü, Ömer; Türüt, AbdülmecitThe current-voltage (I-V) measurements were performed in the temperature range (200-300 K) on Al/DNA/p-Si Schottky barrier type diodes. The Schottky diode shows non-ideal I-V behaviour with ideality factors n equal to 1.34 ± 0.02 and 1.70 ± 0.02 at 300 K and 200 K, respectively, and is thought to have a metal-interface layer-semiconductor (MIS) configuration. The zero-bias barrier height Φb determined from the I-V measurements was 0.75 ± 0.01 eV at 300 K and decreases to 0.61 ± 0.01 eV at 200 K. The forward voltage-temperature (VF-T) characteristics were obtained from the I-V measurements in the temperature range 200-300 K at different activation currents (IF) in the range 20 nA-6 μA. The VF-T characteristics were linear for three activation currents in the diode. From the VF-T characteristics at 20 nA, 100 nA and 6 μA, the values of the temperature coefficients of the forward bias voltage (dV F/dT) for the diode were determined as -2.30 mV K-1, -2.60 mV K-1 and -3.26 mV K-1 with a standard error of 0.05 mV K-1, respectively.Öğe Electronic properties of Cu/n-InP metal-semiconductor structures with cytosine biopolymer(Polska Akademia Nauk, 2015-09) Güllü, Ömer; Türüt, AbdülmecitThis work shows that cytosine biomolecules can control the electrical characteristics of conventional Cu/n-InP metal-semiconductor contacts. A new Cu/n-InP Schottky junction with cytosine interlayer has been formed by using a drop cast process. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Cu/cytosine/n-InP structure were investigated at room temperature. A potential barrier height as high as 0.68 eV has been achieved for Cu/cytosine/n-InP Schottky diodes, which have good I-V characteristics. This good performance is attributed to the effect of interfacial biofilm between Cu and n-InP. By using C-V measurement of the Cu/cytosine/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as a function of frequency. Also, the interface-state density of the Cu/cytosine/n-InP diode was found to vary from 2:24 × 1013 eV-1cm-2 to 5.56× 1012 eV-1 cm-2.Öğe High barrier Schottky diode with organic interlayer(Elsevier, 2012-03) Güllü, Ömer; Aydoğan, Şakir; Türüt, AbdülmecitA new Cu/n-InP Schottky junction with organic dye (PSP) interlayer has been formed by using a solution cast process. An effective barrier height as high as 0.82 eV has been achieved for Cu/PSP/n-InP Schottky diodes, which have good currentvoltage (IV) characteristics. This good performance is attributed to the effect of formation of interfacial organic thin layer between Cu and n-InP. By using capacitancevoltage measurement of the Cu/PSP/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as 0.73 V and 0.86 eV, respectively. From the IV measurement of the diode under illumination, short circuit current (I sc) and open circuit voltage (V oc) have been extracted as 0.33 μA and 150 mV, respectively.
