Şakir Aydoğan

Fabrication and electrical characterization of a silicon Schottky device based on organic material

An Al/methyl violet (MV)/n-Si/AuSb Schottky structure was fabricated and its current–voltage (I–V), capacitance–voltage (C–V) and capacitance–frequency (C–f) characteristics were investigated at room temperature. A modified Nordes function combined with conventional forward I–V method was used to extract the parameters including barrier height (BH) and series resistance. The BH and series resistance obtained from Nordes function have been compared with those from Cheung functions, and it was seen that there is good agreement between the BH values from both methods. It was also seen that the values of capacitance are almost independent of frequency up to a certain value of frequency, whereas at high frequencies the capacitance decreased. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the n-Si that can follow the alternating current (ac) signal.

Effect of temperature on the capacitance–frequency and conductance–voltage characteristics of polyaniline/p-Si/Al MIS device at high frequencies

Abstract A polyaniline/p-Si/Al MIS device has been fabricated by forming a polyaniline layer on Si by using the electrochemical polymerization method. The conductance–voltage and capacitance–frequency measurements have been performed as a function of temperature. The capacitance of the device decreased with increasing frequency. The increase in capacitance results from the presence of interface states. The peaks have been observed in the conductance curves of the device and attributed to the presence of an interfacial layer between polyaniline and p-Si. For each temperature, the plot of series resistance/voltage gave a peak. The voltage and temperature dependence of series resistance has been attributed to the particular distribution density of interface states and the interfacial insulator layer.

The investigation of the electrical properties of Fe3O4/n-Si heterojunctions in a wide temperature range

Monodisperse 8nm Fe3O4 nanoparticles (NPs) were synthesized by the thermal decomposition of iron(III) acetylacetonate in oleylamine and then were deposited onto n-type silicon wafer having the Al ohmic contact. Next, the morphology of the Fe3O4 NPs were characterized by using TEM and XRD. The optical properties of Fe3O4 NPs film was studied by UV-Vis spectroscopoy and its band gap was calculated to be 2.16eV. Au circle contacts with 7.85×10(-3)cm(2) area were provided on the Fe3O4 film via evaporation at 10(-5)Torr and the Au/Fe3O4 NPs/n-Si/Al heterojunction device were fabricated. The temperature-dependent junction parameters of Au/Fe3O4/n-Si/Al device including ideality factor, barrier height and series resistance were calculated by using the I-V characteristics in a wide temperature range of 40-300K. The results revealed that the ideality factor and series resistance increased by the decreasing temperature while the barrier height decreases. The Richardson constant of Au/Fe3O4/n-Si/Al device was calculated to be 2.17A/K(2)cm(2) from the I-V characteristics. The temperature dependence of Au/Fe3O4/n-Si/Al heterojunction device showed a double Gaussian distribution, which is caused by the inhomogeneities characteristics of Fe3O4/n-Si heterojunction.

Synthesis, characterization and diode application of poly(4-(1-(2-phenylhydrazono)ethyl)phenol)

Poly(phenoxy-ketimine)s, which have a conjugated bond system, are a family of polyphenols that can be prepared by oxidative polycondensation reaction from a monomer containing both hydroxyl (–OH) and ketimine side groups. In this context, a novel poly(phenoxy-ketimine), poly(4-(1-(2-phenylhydrazono)ethyl)phenol), abbreviated as poly(4-PHEP), which includes a system of conjugated bonds and active hydroxyl groups, was synthesized and spectroscopically characterized by elemental analysis, FTIR (Fourier transform infrared) spectroscopy, NMR (nuclear magnetic resonance) absorption and fluorescence spectroscopy. The optical band gap of the polymer is determined to be 3.05 eV. In addition, electrical conductivity, solubility and thermal properties of poly(4-PHEP) were determined. Its electrical conductivity was found to be ∼8.55 × 10−2 S cm−1, which is the typical level for semiconductors. Afterwards, a polymer/p-type Si junction device was fabricated, and its rectifying behaviours, depending on some parameters including ideality factor, barrier height and series resistance values at room temperature, were examined by current–voltage (I–V) and capacitance–voltage (C–V) measurements. Consequently, these interesting properties of the polymer reveal that it has potentially beneficial applications in various fields of electronics as semiconducting materials.

Schottky Diode Applications of the Fast Green FCF Organic Material and the Analyze of Solar Cell Characteristics

In this study, a device applications of organic material Fast Green FCF (C37H34N2Na2O10S3Na2) has been investigated. After chemical cleaning process of boron doped H-Si crystals, Al metal was coated on the one surface of crystals by thermal evaporation and fast green organic materials were coated on other surface of crystals with spin coating method (coating parameters; 800 rpm for 60 s). Finally, Ni metal was coated on Fast Green by sputtering and we obtained the Ni/Fast Green FCF/n-Si/Al Schottky type diode. And then we calculated the basic diode parameters of device with current-voltage (I-V) and capacitance- voltage (C-V) measurements at the room temperature. We calculated the ideality factory (n), barrier height (Φb) of rectifing contact from I-V measurements using thermionic emission methods. Furthermore, we calculated ideality factory (n), barrier height (Φb) and series resistance (Rs) of device using Cheung and Norde functions too. The diffusion potential, barrier height, Fermi energy level and donor concentration have been determined from the linear 1/C2-V curves at reverse bias, at room temperature and various frequencies. Besides we measured the current-voltage (I-V) at under light and analyzed the characteristics of the solar cell device.