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    Analysis of surface states and series resistance in Au/n-Si Schottky diodes with insulator layer using current-voltage and admittance-voltage characteristics
    (Pergamon-Elsevier Science Ltd, 2009) Altındal, Şemsettin; Yücedağ, İbrahim; Tataroğlu, Adem
    In order to good interpret the experimentally observed Au/n-Si (metal-semiconductor) Schottky diodes with thin insulator layer (18 angstrom) parameters such as the zero-bias barrier height (Phi(bo)), ideality factor (n), series resistance (R-s) and surface states have been investigated using current-voltage (I-V), capacitance-frequency (C-f) and conductance-frequency (G-f) techniques. The forward and reverse bias I-V characteristics of Au/n-Si (MS) Schottky diode were measured at room temperature. In addition, C-f and G-f characteristics were measured in the frequency range of 1 kHz-1 MHz. The higher values of C and G at low frequencies were attributed to the insulator layer and surface states. Under intermediate forward bias, the semi-logarithmic Ln (I)-V plot shows a good linear region. From this region, the slope and the intercept of this plot on the current axis allow to determine the ideality factor (n). the zero-barrier height (Phi(bo)) and the saturation current (I-s) evaluated to 2.878, 0.652 and 3.61 x 10(-7) A, respectively. The diode shows non-ideal I-V behavior with ideality factor greater than unity. This behavior can be attributed to the interfacial insulator layer, the surface states, series resistance and the formation barrier inhomogeneity at metal-semiconductor interface. From the C-f and G-f characteristics, the energy distribution of surface states (N-ss) and their relaxation time (tau) have been determined in the energy range of (E-c-0.493E(v))-(E-c-0.610) eV taking into account the forward bias I-V data. The values of N-ss and tau change from 9.35 x 10(13) eV(-1) cm(-2) to 2.73 x 10(13) eV(-1) cm(-2) and 1.75 x 10(-5) s to 4.50 x 10(-4) s, respectively. (C) 2009 Elsevier Ltd. All rights reserved.
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    Dielectric characteristics of gamma irradiated Au/SnO2/n-Si/Au (MOS) capacitor
    (Elsevier Sci Ltd, 2014) Tataroğlu, Adem; Yıldırım, Mert; Baran, Halil Mert
    The dielectric characteristics of gamma irradiated Au/SnO2/n-Si/Au (MOS) capacitor were studied. The MOS capacitor was irradiated by a Co-60 gamma radiation source with a dose rate of 0.69 kGy/h. The dielectric parameters such as dielectric constant (epsilon'), dielectric loss (epsilon ''), loss factor (tan delta) and ac electrical conductivity (sigma(ac)) were calculated from the capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements. It is found that the C and G/omega values decrease with the increasing total dose due to the irradiation-induced defects at the interface. Also, the calculated values of epsilon', epsilon '' and sigma(ac) are found to decrease with an increased radiation dose. This result indicates that the dielectric characteristics of the MOS capacitor are sensitive to gamma-ray dose. (C) 2014 Elsevier Ltd. All rights reserved.
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    The effect of temperature on the electrical characteristics of Ti/n-GaAs Schottky diodes
    (Elsevier, 2022) Durmuş, Haziret; Tataroğlu, Adem; Altındal, Şemsettin; Yıldırım, Mert
    Schottky diodes still attract researchers as they are used in various device applications. This study provides I-V characteristics of Ti/n-GaAs (80-300 K). Higher barrier height (phi B0) values were obtained for higher tempera-tures, whereas the ideality factor exhibited the opposite behavior. This was associated with a barrier in -homogeneity at the Ti/GaAs interface, which has a Gaussian distribution (GD). The mean barrier height values calculated from the modified Richardson and phi B0 -q/2 kT plots were found to be 0.584 eV and 0.575 eV in the temperature range of 80-160 K. They were found as 1.041 eV and 1.033 eV between 180 K and 300 K, respectively. The modified Richardson constant value, on the other hand, was calculated as 22.06 A cm-2 K-2 (80-160 K) and 13.167 A cm-2 K-2 (180-300 K). These values are higher than the theoretical value for n-GaAs, which is 8.16 A cm-2 K-2. This difference may stem from intense inhomogeneity at the Ti/n-GaAs interface.