Frequency and gate voltage effects on the dielectric properties and electrical conductivity of Al/SiO2/p-Si metalinsulator-semiconductor Schottky diodes Fabrication and properties of metal/ferroelectrics/semiconductor diodes on 4H-SiC Appl.In order to determine the effective current-conduction mechanisms in Au/TiO 2 /n-4H-SiC (metalinsulator semiconductor) type Schottky barrier diodes (SBDs), their current-voltage (I-V) measurements were carried out in the temperature range of 200-380 K. Some electrical parameters, such as ideality factor (n), zero-bias barrier height (BH) (U Bo ), series and shunt resistances (R s , R sh ), were obtained as 5.09, 0.81 eV, 37.43 X, and 435 kX at 200 K and 2.68, 0.95 eV, 5.99 X, and 73 kX at 380 K, respectively. The energy density distribution profile of surface states (N ss ) was extracted from the forward-bias I-V data by taking into account voltage dependent of the ideality factor (n V ), effective BH (U e ), and R s for 200, 300, and 380 K. The Ln(I) vs V plots are completely parallel in the intermediate bias voltages, which may be well explained by field emission (FE) mechanism for each temperature. On the other hand, the high value of n cannot be explained with this mechanism. Therefore, to explain the change in BH and n with temperature, U Bo vs q/2kT plot was drawn to obtain an evidence of a Gaussian distribution (GD) of the BHs and thus the mean value of BH ( U Bo ) and standard deviation (r so ) values were found from this plot as 1.396 eV and 0.176 V, respectively. The U Bo and Richardson constant (A*) values were found as 1.393 eV and 145.5 A.cm À2 K À2 using modified Ln(I o /T 2 )-(q 2 r s 2 /2k 2 T 2 ) vs q/kT plot, respectively. It is clear that all of the obtained main electrical parameters were found as a strong function of temperature. These results indicated that the current conduction mechanism in Au/TiO 2 /n-4 H-SiC (SBD) well obey the FE and GD mechanism rather than other mechanisms. V C 2014 AIP Publishing LLC.
In order to see the effect of Bi-doped PVA interfacial layer on electrical characteristics, both Au/n-Si (MS) and Au/Bidoped PVA/n-Si (MPS) type Schottky barrier diodes (SBDs) were fabricated, and their main electrical parameters were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements, in dark and under illumination at room temperature. Forward bias semi-logarithmic I-V plots of these SBDs show two distinct linear regions, with different slopes in the low and intermediate voltage region. Such behavior in I-V plots was explained by two parallel diodes model. Experimental results show that the ideality factor (n), barrier height (φ b ), series and shunt resistances (R s and R sh ), and the density of interface states/traps (N ss ) are strong functions of illumination level and applied bias voltage. The R s values were determined from the I-V characteristics, by using both Ohm's law. The energy distribution profile of N ss was also obtained from the forward bias I-V characteristics, by taking into account voltage dependent barrier height (φ e ) and ideality factor (n). It was found that Bi-doped PVA layer lead to a considerable decrease in the leakage current, R s and N ss and increase in R sh and rectifier rate (RR=I F /I R ). In conclusion, a thin Bi-doped PVA interfacial layer, considerably improved the diode performance, both in dark and under illumination.account voltage dependent barrier height (φ B (V)) and ideality factor n(V). Experimental results show that the Bi-doped interfacial PVA layer led to considerable decrease in the leakage current, R s and N ss and led to increase in R sh and rectifier rate (RR=I F /I R ). So, it can be said that Bi-doped PVA considerably improved the performance of SBD. Experimental ProcedureFor the fabrication of Au/PVA (Bi-doped)/n-Si (MPS), (phosphor doped) single crystal silicon with surface orientation, 350 μm thickness and 0.7 Ω.cm resistivity was used. Si wafer was degreased in organic solution of peroxide-ammoniac solution in 10 minutes, and then etched in a sequence of H 2 O+HCl solution, and finally quenched in de-ionized water resistivity of 18 MΩ.cm for a prolonged time. Preceding each cleaning step, the wafer was rinsed thoroughly in de-ionized water. Immediately after surface cleaning, high purity (99.999%) gold (Au), with a thickness of ~2000Å, was thermally evaporated onto the whole back side of Si wafer, in a pressure about 10 -6 Torr in high vacuum metal evaporation system. In order to perform a low resistivity ohmic back metal contact, n-Si wafer was sintered at about 450°C for 5 min in N 2 atmosphere.Immediately after the formation of ohmic contact, 0.5 g of bismuth acetate was mixed with 50 g of polyvinyl Alcohol (PVA), molecular Citation: Alialy S, Tecimer H, Uslu H, Altındal Ş (2013) A Comparative Study on Electrical Characteristics of Au/N-Si Schottky Diodes, with and Without Bi-Doped PVA
The dielectric properties of Au/(1 % graphene doped-Ca 1.9 Pr 0.1 Co 4 O x )/n-Si structures were investigated by the impedance spectroscopy method including capacitance-voltage (C-V) and conductance-voltage (G/x-V) measurements in the frequency range of 10-2 MHz at room temperature. The experimental results show that the real and imaginary parts of dielectric constant (e 0 , e 00 ) and electric modulus (M 0 and M 00 ), and ac electrical conductivity (r ac ) are a strong functions of frequency and voltage, both. Negative dielectric constant behavior was observed at sufficiently high forward bias voltages at low frequencies and it was attributed to the interfacial polarization, interface traps and series resistance. e 0 decreases with increasing frequency at sufficiently high biases whereas e 00 increases. Since interfacial polarization and interface states, both, can follow the ac external signal easily at low frequencies, there occurs a contribution to the measured capacitance and conductance. The negative values of e 0 correspond to maximum value of e 00 . Such contrary behavior in the e 0 and e 00 appears as an abnormality when compared to the conventional behavior metal-semiconductor structures with and without interfacial layer. Experimental results confirmed that the dielectric properties of these structures are quite sensitive to the frequency and applied bias voltage, both, especially at low frequencies and high voltages because of density distribution of interface states and interfacial polarization.
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