Browsing by Author "Temirci, C"

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The Current-Voltage and Capacitance-Voltage Characteristics of Cu/Rhodamine 101/P-si Contacts
(Elsevier, 2004) Temirci, C; Çakar, M
The organic compound rhodamine 101 (Rh 101) was evaporated on the surface of an inorganic semiconductor p-type Si substrate. The current-voltage (I - V) and capacitance-voltage (C - V) measurements of the samples were carried out at room temperature and in the dark. From the I - V characteristics it was seen that the Cu/Rh 101/p-Si contacts show a rectifying behavior. An ideality factor value of 1.54 and a barrier height value of 0.78eV for the Cu/Rh 101/p-Si contact were determined from the forward bias I - V characteristics. A barrier height value of 0.97 eV was obtained from the capacitance voltage (C - V) characteristics. It has been seen that the values of the barrier height are significantly larger than those of conventional Schottky diodes. (C) 2004 Elsevier B.V. All rights reserved.
Dependence of Thermal Annealing on the Density Distribution of Interface States in Ti/N-gaas(te) Schottky Diodes
(Elsevier Science Bv, 1999) Ayyildiz, E; Bati, B; Temirci, C; Türüt, A
The Ti/n-GaAs(Te) Schottky barrier diodes have been annealed in the temperature range 200-400 degrees C with steps of 100 degrees C for 5 min. The barrier height value has increased with increasing annealing temperature. This increase has been attributed to that the annealing removes the passivation effect of the native oxide layer and reactivates the surface defects which are responsible for the Fermi level pinning. The value of equilibrium interface charge density Q(ss)(0) has increased with increasing annealing temperature. It has been found that the experimental density distribution curves of the interface states and the values of equilibrium interface charge density Q(ss)(0) has confirmed this interpretation. The results indicate that the negative equilibrium interface charge is responsible for the actual equilibrium barrier height value. (C) 1999 Elsevier Science B.V. All rights reserved.
Determination of the Density Distribution of Interface States From High- and Low-Frequency Capacitance Characteristics of the Tin/Organic Pyronine-b/P-type Silicon Structure
(Wiley-v C H verlag Gmbh, 2002) Çakar, M; Temirci, C; Türüt, A
The interface state energy distribution curve of the Sn/ pyronine-B/p-Si Schottky diode has been obtained from its forward-bias C-HF and C-IF characteristics (see picture). The interface state density value rises exponentially with bias from the midgap towards the top of the valence band. The interface states and interfacial layer at the organic semiconductor/ inorganic semiconductor structures play an important role in the determination of the Schottky barrier height.
The Effect of Series Resistance on Calculation of the Interface State Density Distribution in Schottky Diodes
(Taylor & Francis Ltd, 2001) Ayyildiz, E; Temirci, C; Bati, B; Türüt, A
This work presents an attempt related to the importance of the fact that the series resistance value is considered in calculating the interface state density distribution from the non-ideal forward bias current-voltage (I-V) characteristics of Au/n-Si Schottky barrier diodes (SBDs). To examine the consistency of this approach, Au/n-Si SBDs with Si bulk thicknesses of 200 and 400 mum have been prepared. Both diodes showed non-ideal I-V behaviour with ideality factors of 1.14 and 1.12, respectively, and thus it has been thought that the diodes have a metal-interface layer-semiconductor configuration. At the same energy position near the bottom of the conduction band, the interface state density (N-SS) values, without taking into account the series resistance value of the devices, are almost one order of magnitude larger than the N-SS values obtained taking into account the series resistance value.
Effect of Thermal Annealing on Co/N-lec Gaas (Te) Schottky Contacts
(Pergamon-elsevier Science Ltd, 2000) Nuhoglu, Ç; Temirci, C; Bati, B; Biber, M; Türüt, A
The Co/n-GaAs(Te) Schottky barrier diodes have been annealed at temperatures from 100 to 300 degrees C for 5 min and from 350 to 800 degrees C for 1 min in N-2 atmosphere. Some expressions have been obtained to interpret the relation between the experiment barrier height Phi(b,o) and equilibrium interface charge density Q(ss)(0) depending on annealing temperature. The Phi(b,o) value has increased and Q(ss)(0) is decreased with increasing annealing temperature up to 550 degrees C. This increase in the barrier height has been attributed to the value of positive Q(ss)(0), which is responsible for the Fermi level pinning. The relation between the Phi(b,o), and Q(ss)(0) depending on annealing temperature is in very good agreement with that of the interface state density distribution especially in the mid-gap. (C) 2000 Elsevier Science Ltd. All rights reserved.
Equilibrium Properties of a Spin-1 Ising System With Bilinear, Biquadratic and Odd Interactions
(Elsevier Science Bv, 1996) Temirci, C; Kokce, A; Keskin, M
The equilibrium properties of the spin-1 Ising system Hamiltonian with arbitrary bilinear (J), biquadratic (K) and odd (L), which is also called dipolar-quadrupolar, interactions is studied for zero magnetic field in the lowest approximation of the cluster variation method. The odd interaction is combined with the bilinear (dipolar) and biquadratic (quadrupolar) exchange interactions by the geometric mean. In this system, phase transitions depend on the ratio of the coupling parameters, alpha = J/K; therefore, the dependence of the nature of the phase transition on alpha is investigated extensively and it is found that for alpha less than or equal to 1 and alpha greater than or equal to 2000 a second-order phase transition occurs, and for 1 < alpha < 2000 a first-order phase transition occurs. The critical temperatures in the case of a second-order phase transition and the upper and lower limits of stability temperature in the case of a first-order phase transition are obtained for different values of alpha calculated using the Hessian determinant. The first-order phase transition temperatures are found by using the free energy values while increasing and decreasing the temperature. Besides the stable branches of the order parameters, we establish also the metastable and unstable parts of these curves and the thermal variations of these solutions as a function of the reduced temperature are investigated. The unstable solutions for the first-order phase transitions are obtained by displaying the free energy surfaces in the form of a contour map. Results are compared with the spin-1 Ising system Hamiltonian with the bilinear and biquadratic interactions and it is found that the odd interaction greatly influences the phase transitions.
Low- and High-Frequency C-V Characteristics of the Contacts Formed by Sublimation of the Nonpolymeric Organic Compound on P-Type Si Substrate
(Wiley-v C H verlag Gmbh, 2004) Temirci, C; Çakar, M; Türüt, A; Onganer, Y
The Sn/pyronine-B/p-Si Schottky structures have been obtained by sublimation of the organic compound pyronine-B onto the top of a p-Si surface. Barrier height and ideality factor value of 0.79 eV and 1.13, respectively, for the device have been determined from the forward-bias current-voltage (I-V characteristics. The interface state density obtained from the forward bias high and low capacitance-voltage characteristics increases exponentially with bias between the midgap and the top of the valance band, from 2.15 x 10(11) cm(-2) eV(-1) at (0.79-E-v) eV to 1.16 x 10(12) cm(-1) eV(-1) at (0.53-E-v) eV. These values have been compared to those of the metal/Si structures in the literature, and it is seen that the presence of the nonreactive organic materials at the inorganic semiconductor and metal interface may obstruct the generation of the interface states at the semiconductor surface that strongly influence the Schottky barrier formation. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
The Schottky Barrier Height of the Rectifying Cu/Pyronline-b Au/Pyronine-b Sn/Pyronine-b and Al/Pyronine-b Contacts
(Elsevier Science Sa, 2004) Çakar, M; Temirci, C; Türüt, A
The Cu/pyronine-B/p-Si, Au/pyronine-B/p-Si, Al/pyronine-B/p-Si and Sn/pyronine-B/p-Si Schottky structures have been obtained by sublimation of the organic compound pyronine-B onto the top of p-Si surface. Our goal is to experimentally investigate whether or not a nonpolymeric organic compound as contact to an inorganic semiconductor such as Si can provide the continuous control of the barrier height (BH). The barrier height Phi(bp) values of 0.51, 0.674, 0.75 and 0.79 eV for the Cu/pyronine-B/p-Si, Au/pyronine-B/p-Si, Al/pyronine-B/P-Si and Sn/pyronine-B/p-Si Schottky structures have obtained from the forward current-voltage (I-V) characteristics. It has been seen that the values of Phi(bp) are significantly larger than those of conventional Schottky diodes. (C) 2003 Elsevier B.V. All rights reserved.
Temperature Dependence of the Current-Voltage Characteristics of the Al/Rhodamine-101 Contacts
(Elsevier, 2006) Karatas, S; Temirci, C; Çakar, M; Türüt, A
The current-voltage (I-V) characteristics of Al/Rhodamine-101/p-Si/Al contacts have been measured at temperatures ranging from 280 to 400 K at 20 K intervals. A barrier height (BH) value of 0.817 eV for the Al/Rh101/p-Si/Al contact was obtained at the room temperature that is significantly larger than the value of 0.58 eV of the conventional Al/p-Si Schottky diode. While the barrier height Phi(b0) decreases the ideality factors (n) become larger with lowering temperature. The high values of n depending on the sample temperature may be ascribed to decrease of the exponentially increase rate in current due to space-charge injection into Rh101 thin film at higher voltage. Therefore, at all temperatures, it has been seen that the I-V characteristics show three different regions, the ohmic behavior at low voltages, and the space charge limited current with an exponential distribution of traps at high voltages. (c) 2005 Elsevier B.V. All rights reserved.