Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 7Citation - Scopus: 6Anisotropic Etching of Cvd Grown Graphene for Ammonia Sensing(Institute of Electrical and Electronics Engineers Inc., 2022) Yağmurcukardeş, Nesli; Bayram, Abdullah; Aydın, Hasan; Yağmurcukardeş, Mehmet; Açıkbaş, Yaser; Peeters, François M.; Çelebi, CemBare chemical vapor deposition (CVD) grown graphene (GRP) was anisotropically etched with various etching parameters. The morphological and structural characterizations were carried out by optical microscopy and the vibrational properties substrates were obtained by Raman spectroscopy. The ammonia adsorption and desorption behavior of graphene-based sensors were recorded via quartz crystal microbalance (QCM) measurements at room temperature. The etched samples for ambient NH3 exhibited nearly 35% improvement and showed high resistance to humidity molecules when compared to bare graphene. Besides exhibiting promising sensitivity to NH3 molecules, the etched graphene-based sensors were less affected by humidity. The experimental results were collaborated by Density Functional Theory (DFT) calculations and it was shown that while water molecules fragmented into H and O, NH3 interacts weakly with EGPR2 sample which reveals the enhanced sensing ability of EGPR2. Apparently, it would be more suitable to use EGRP2 in sensing applications due to its sensitivity to NH3 molecules, its stability, and its resistance to H2O molecules in humid ambient.Article Citation - WoS: 8Citation - Scopus: 10Experimental and Computational Investigation of Graphene/Sams Schottky Diodes(Elsevier Ltd., 2018) Aydın, Hasan; Bacaksız, Cihan; Yağmurcukardeş, Nesli; Karakaya, Caner; Mermer, Ömer; Can, Mustafa; Senger, Ramazan Tuğrul; Şahin, Hasan; Selamet, YusufWe 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″-terphenyl-5′ carboxylic acids (TPA) and 4,4-di-9H-carbazol-9-yl-1,1′:3′1′-terphenyl-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 (R s ) 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 π–π 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.Article Citation - WoS: 4Citation - Scopus: 4Effect of Aromatic Sams Molecules on Graphene/Silicon Schottky Diode Performance(Electrochemical Society, Inc., 2016) Yağmurcukardeş, Nesli; Aydın, Hasan; Can, Mustafa; Yanılmaz, Alper; Mermer, Ömer; Okur, Salih; Selamet, YusufAu/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 φB 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.