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    Current-conduction mechanism in Au/n-4H-SiC Schottky barrier diodes
    (Natl Inst Science Communication-Niscair, 2015) Kaya, A.; Sevgili, O.; Altindal, S.; Ozturk, M. K.
    Au/n-4H-SiC Schottky barrier diodes (SBDs) were fabricated and their temperature and voltage dependence of saturation current (I-o), ideality factor (n), bather height (Phi(bo)), series and shunt resistances (R-s, R-th) values were obtained by using current-voltage (I-V) measurements in the temperature range 110-400 K. The values of I-0, n and Phi(bo) were found as 3.00x10(-14)A, 3.41 and 0.39. eV at 110 K and 7.75x10(-7)A, 1.64 and 0.90 eV at 400 K, respectively. The Phi(bo)-q/2kT plot was drawn to obtain an evidence of a Gaussian distribution (GD) of the bather heights (BHs). The mean BH ((Phi) over bar (bo)) and standard deviation (sigma(o)) values have been extracted from the intercept and slope of this plot is as 1.089 eV and 0.127 V, respectively. The (Phi) over bar (bo) and Richardson constant (A*) values were obtained from the modified Ln(I-o/T-2) -(q(2)sigma(2)(s)/2k(2)T(2)) versus q/kT plot as ;1.093 eV and 160.6 A.cm(-2)K(-2) which can be considered as close to the theoretical value 146 A.cm(-2)K(-2), respectively. Voltage dependent activation energy (E-a) value was also obtained from the In(I-o/T-2)-q1/kT and In(I-o/T-2)-qI/nkT plots in the voltage range 0.05-0.50 V with 0.05 V steps and it is found that it decreases with increasing voltage. The temperature dependence of I-V characteristics in Au/n-4H-SiC diodes can be successfully explained on the basis of a TB mechanism with GD of the BHs.
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    Energy density distribution profiles of surface states, relaxation time and capture cross-section in Au/n-type 4H-SiC SBDs by using admittance spectroscopy method
    (World Scientific Publ Co Pte Ltd, 2014) Kaya, A.; Sevgili, O.; Altindal, S.
    Au/n-type 4H-SiC diodes were fabricated and their electrical characteristics have been investigated by using the capacitance/conductance-voltage-frequency (C-V -f and G/w - V f) measurements method at room temperature. The main parameters such as the doping atoms (N-D), diffusion potential (V-D) and barrier height (Phi(B)(C-V)) values were obtained from the reverse bias C-2 - V plots for each frequency. C and G/omega values decrease with increasing frequency as almost exponential for each voltage and these changes in C and G/omega are considerably high at low frequencies due to the contribution of surface states (N-ss) to the measured C and G/omega. The resistivity (Ri) versus V plots were also obtained by using the C and G data and they exhibit an anomalous peak which is corresponding to the depletion region at each frequencies and its magnitude decreases with increasing frequency. The energy density distribution of N-ss and their relaxation time (tau) were obtained from the conductance method and they range from 1.53 x 10(14) eV(-1) cm(-2) to 1.03 x 10(14) eV(-1) cm(-2) and 1.29 x 10(-4) s to 3.35 x 10(-5) s, respectively, in the energy range of (0.585 - E-v) - (0.899 - E-v) eV. The voltage dependent of N-ss was also obtained from C-HF - C-LF method. The obtained value of N-ss is about 10(14) eV(-1) cm(-2) order and these values are suitable for an electronic device.