Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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Department: search.filters.department.İzmir Institute of Technology. PhotonicsInstitution Author: search.filters.institutionAuthor.Şenger, Ramazan Tuğrul

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 8
    Citation - Scopus: 10
    Experimental and Computational Investigation of Graphene/Sams Schottky Diodes
    (Elsevier Ltd., 2018) Aydın, Hasan; Bacaksız, Cihan; Senger, Ramazan Tuğrul; Karakaya, Caner; Mermer, Ömer; Selamet, Yusuf; Senger, Ramazan Tuğrul; Şahin, Hasan; Şahin, Hasan; 04.04. Department of Photonics; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    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″-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: 12
    Citation - Scopus: 12
    Ultra-Thin Znse: Anisotropic and Flexible Crystal Structure
    (Elsevier Ltd., 2017) Bacaksız, Cihan; Şenger, Ramazan Tuğrul; Şahin, Hasan; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    By performing density functional theory-based calculations, we investigate the structural, electronic, and mechanical properties of the thinnest ever ZnSe crystal [11]. The vibrational spectrum analysis reveals that the monolayer ZnSe is dynamically stable and has flexible nature with its soft phonon modes. In addition, a direct electronic band gap is found at the gamma point for the monolayer structure of ZnSe. We also elucidate that the monolayer ZnSe has angle dependent in-plane elastic parameters. In particular, the in-plane stiffness values are found to be 2.07 and 6.89 N/m for the arm-chair and zig-zag directions, respectively. The angle dependency is also valid for the Poisson ratio of the monolayer ZnSe. More significantly, the in-plane stiffness of the monolayer ZnSe is the one-tenth of Young modulus of bulk zb-ZnSe which indicates that the monolayer ZnSe is a quite flexible single layer crystal. With its flexible nature and in-plane anisotropic mechanical properties, the monolayer ZnSe is a good candidate for nanoscale mechanical applications.
  • Article
    Citation - WoS: 22
    Citation - Scopus: 22
    Electronic and Magnetic Properties of 1t-Tise2 Nanoribbons
    (IOP Publishing Ltd., 2015) Özaydın, H. Duygu; Şahin, Hasan; Şahin, Hasan; Peeters, François M.; Şenger, Ramazan Tuğrul; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Motivated by the recent synthesis of single layer TiSe2,we used state-of-the-art density functional theory calculations, to investigate the structural and electronic properties of zigzag and armchairedged nanoribbons (NRs) of this material. Our analysis reveals that, differing from ribbons of other ultra-thin materials such as graphene, TiSe2 NRs have some distinctive properties. The electronic band gap of the NRs decreases exponentially with the width and vanishes for ribbons wider than 20 Å. For ultranarrow zigzag-edged NRs we find odd-even oscillations in the band gap width, although their band structures show similar features. Moreover, our detailed magnetic-ground-state analysis reveals that zigzag and arm chair edged ribbons have non-magnetic ground states. Passivating the dangling bonds with hydrogen at the edges of the structures influences the band dispersion. Our results shed light on the characteristic properties of T phase NRs of similar crystal structures.