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Öğe Effect of Aromatic SAMs Molecules on Graphene/Silicon Schottky Diode Performance(Electrochemical Soc Inc, 2016) Yagmurcukardes, N.; Aydin, H.; Can, M.; Yanilmaz, A.; Mermer, O.; Okur, S.; Selamet, Y.Au/n-Si/Graphene/Au Schottky diodes were fabricated by transferring atmospheric pressure chemical vapor deposited (APCVD) graphene on silicon substrates. Graphene/n-Si interface properties were improved by using 5-[(3-methylphenyl)(phenyl) amino] isophthalic acid (MePIFA) and 5-(diphenyl) amino] isophthalic acid (DPIFA) aromatic self-assembled monolayer (SAM) molecules. The surface morphologies of modified and non-modified films were investigated by atomic force microscopy and scanning electron microscopy. The surface potential characteristics were obtained by Kelvin-probe force microscopy and found as 0.158 V, 0.188 V and 0,383 V as a result of SAMs modification. The ideality factors of n-Si/Graphene, n-Si/MePIFA/Graphene and n-Si/DPIFA/Graphene diodes were found as 1.07, 1.13 and 1.15, respectively. Due to the chain length of aromatic organic MePIFA and DPIFA molecules, also the barrier height phi(B) values of the devices were decreased. While the barrier height of n-Si/Graphene diode was obtained as 0.931 eV, n-Si/MePIFA/Graphene and n-Si/DPIFA/Graphene diodes have barrier height of 0.820 and 0.720 eV, respectively. (C) 2016 The Electrochemical Society. All rights reserved.Öğe Experimental and computational investigation of graphene/SAMs/n-Si Schottky diodes(Elsevier Science Bv, 2018) Aydin, H.; Bacaksiz, C.; Yagmurcukardes, N.; Karakaya, C.; Mermer, O.; Can, M.; Senger, R. T.; Sahin, H.; Selamet, Y.We have investigated the effect of two different self-assembled monolayers (SAMs) on electrical characteristics of bilayer graphene (BLG)/n-Si Schottky diodes. Novel 4"bis(diphenylamino)-1, 1':3"-terpheny1-5' carboxylic acids (TPA) and 4,4-di-9H-carbazol-9-y1-1,1':3'1'-terpheny1-5' carboxylic acid (CAR) aromatic SAMs have been used to modify n-Si surfaces. Cyclic voltammetry (CV) and Kelvin probe force microscopy (KPFM) results have been evaluated to verify the modification of n-Si surface. The current-voltage (I-V) characteristics of bare and SAMs modified devices show rectification behaviour verifying a Schottky junction at the interface. The ideality factors (n) from ln(I)-V dependences were determined as 2.13,1.96 and 2.07 for BLG/n-Si, BLG/TPA/n-Si and BLG/CAR/n-Si Schottky diodes, respectively. In addition, Schottky barrier height (SBH) and series resistance (Rs) of SAMs modified diodes were decreased compared to bare diode due to the formation of a compatible interface between graphene and Si as well as n-n interaction between aromatic SAMs and graphene. The CAR-based device exhibits better diode characteristic compared to the TPA-based device. Computational simulations show that the BLG/CAR system exhibits smaller energy-level-differences than the BLG/TPA, which supports the experimental findings of a lower Schottky barrier and series resistance in BLG/CAR diode. (C) 2017 Elsevier B.V. All rights reserved.Öğe Investigation of the Electrical Parameters of the Organic Diode Modified with 4-[(3-Methylphenyl)(phenyl)amino] Benzoic Acid(Electrochemical Soc Inc, 2016) Havare, A. Kemal; Can, M.; Yagmurcukardes, N.; Yigit, M. Z.; Aydin, H.; Okur, S.; Demic, S.; Icli, S.4-[(3-Methylphenyl)(phenyl)amino]benzoic acid (MPPBA) self-assembled monolayer (SAM) molecules as hole injection is formed on p and n type Si and on indium-tin oxide (ITO) electrodes to investigate the effect on the electrical parameters of hole only organic device. The hole mobility improvement of organic device was attributed to an intermediate energy level formed between hole transport materials (HTL) (N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine -NPB) and ITO when forming an ultrathin MPPBA layer, leading to increase of carrier mobility of the device. Space charge limited current (SCLC) technique is used to estimate the mobility of the NPB formed at the interface metal/organic Ohmic contact. The hole mobility of ITO/NPB/Al and ITO/MPPBA/NPB/Al devices were obtained as 1.80 x 10(-6) and 1.76 x 10(-3) cm(2)/Vs, at 1350 E (V/cm)(1/2) applied electric field, respectively. SAM modified devices has lower barrier height values. The electronic characteristic parameters of the ITO/(with or without MPPBA)/NPB/Al, Au/n-Si(or p-Si)/(with or without MPPBA)/Au contacts were calculated using current-voltage (I-V) measurements by Schottky type carrier injection. (C) The Author(s) 2016. Published by ECS.Öğe Polyacrylonitrile (PAN)/carbon nanotube (CNT) electrospun nanofibers: synthesis, characterization, their biocompatibility for L929 fibroblast cells and molecular docking studies(Taylor and Francis Ltd., 2023) Ince, Yardimci, A.; Mutlu, D.; Istifli, E.S.; Arslan, S.; Mahaleh, S.P.G.; Yagmurcukardes, N.; Kara, P.There has been an important interest in to use of electrospun nanomaterials for tissue engineering applications due to the excellent scaffold-cell interaction provided by high interconnectivity and high porosity by electrospun nanofibers. In this study, Polyacrylonitrile (PAN) and carbon nanotube-inserted PAN (PAN/CNT) nanofibers were produced by the electrospinning method and characterized by SEM, FT-IR, and EIS spectroscopy. Both PAN and PAN/CNT nanofibers were obtained beadless and ordered with the average fiber diameters of 277.61 ± 43.6 and 171.01 ± 48.4, respectively. The influence of CNT addition on PAN nanofibers was observed with the decrease of diameter and increase of electrical conductivity of nanofibers. Then, the biocompatibility of PAN and PAN/CNT nanofibers was evaluated by the MTT and AO/EB double-staining experiments. It was observed that the nanofibers showed no cytotoxic effect on L929 fibroblast cells. In the docking experiments, while both PAN and PAN/CNT showed energetically favorable interactions (?G = ?4.60 kcal/mol; ?7.26 kcal/mol, respectively) with the membrane bilayer complex, PAN/CNT formed a more stable binding with the cellular membrane compared to PAN alone. Docking results mechanistically support the more effective increase in the proliferation of L929 fibroblasts at high concentrations in vitro, as PAN/CNT exhibits stronger binding affinity and interaction with the cellular membrane. The increase in electrical conductivity of nanofibers influenced the proliferation positively, as well. © 2023 Taylor & Francis Group, LLC.
