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چکیده
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Organic field effect transistors (OFETS) are considered one of the important devices in various electronic applications due to their distinguished properties such as Lower leakage current, Lower threshold voltage, higher Ion/ Ioff, light weight, small size, high performance and ease of manufacturing. In the present work, new nano composite materials (PVA / SiO2 / NiPc, PVA / SiO2) have been synthesized and tested, to see if they can be suggested as a suiT. element for the future of OFET devices. In this regard, the effect of shrinking the, for instance gate dielectric thickness down to nano meter scale on the optical (say, their optical sensitivity in the presence of light and dark) and electrical properties and its performance of has been investigated. Indeed, in the present study, different thicknesses of PVA polymer (without PVA, 210 nm, 300 nm) were deposited on the gate dielectric material, (here on 300 nm of SiO2 layer). Then the NiPc layer (as an active layer and obviously suiT. optical characteristics ) was also deposited on cited polymer. The effect of different concentrations of PVA polymer as a precursor stage in this regard was also studied to find the changes of the absorption peak in the UV- vis spectra and optical properties associated with the different concentrations of mixtures (PVA & NiPc) on the properties of the solutions for the subsequent use of these transients as an active layer. Different types of deposition techniques were used to prepare OFETS, labelled with (OFET-1, OFET-2 and OFET-3 sample), in where the Physical Vapor Deposition (PVD) equipment was used in this work. Parallel to stated work, SiO2, NiPc, Au, Al are elements of present OFET devices. Fourier Transform Infra-Red (FT-IR) and X- Ray Diffraction patterns (XRD) were used to characterize the compositions, crystallite phases, the size of crystallites, chemical bonds and structure of the present samples. Optical methods were also used, such as the light diffraction method in the Ellipsometer to measure the thickness of deposited films. It was also confirmed by examining the cross-section thickness of the samples with sem. Power supply, multi-meter Kenthly, power meter and electrical circuit have been used to evaluate and measure drain- source current (Ids), drain- source voltage (Vds), capacity of present samples (Ci), carrier mobility (µ), and threshold voltage (Vth) of samples as a possible candidate for the next OFETS generation. Also, light and dark box is used to study the light sensitivity of the samples, The obtained results indicated that using (bilayer gate dielectrics) could be improved the performance of the OFET. The architecture of bilayer gate insulator(PVA/SiO2) increases carrier mobility and improves (Ion/Ioff )ratio with comparing the current gate dielectric, SiO2 of complementary metal oxide semiconductor (CMOS) transistors. Moreover, it is a phototransistor, too.
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