Physics / Fizik

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

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Institution Author: search.filters.institutionAuthor.Ünsal, Elif

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  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Hydrogenated Derivatives of Hexacoordinated Metallic Cu2si Monolayer
    (Royal Society of Chemistry, 2018) Ünsal, Elif; İyikanat, Fadıl; Şahin, Hasan; Senger, Ramazan Tuğrul
    Herein, we carried out first-principles calculations based on density functional theory to investigate the effects of surface functionalization with hydrogen atoms on structural, dynamical and electronic properties of Cu2Si monolayer. Pristine Cu2Si, a metallic monolayer, has a planar hexacoordinate structure. Calculations revealed that the most favorable position of a single H atom on the Cu2Si monolayer is at the top of a Si site. Derivatives of Cu2Si monolayer with various H concentrations were investigated, and by performing phonon calculations, it was found that there are three stable hydrogenated structures. Specific heat of these monolayers was found to increase with the hydrogen concentration at temperatures higher than 100 K. Electronically, the hydrogenated derivatives of Cu2Si monolayer preserve the metallic character.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 11
    Stable Monolayer ?-Phase of Cdte: Strain-Dependent Properties
    (Royal Society of Chemistry, 2017) Ünsal, Elif; Senger, Ramazan Tuğrul; Şahin, Hasan
    CdTe is a well known and widely used binary compound for optoelectronic applications. In this study, we propose the thinnest, free standing monolayer of CdTe which has a tetragonal-PbO (α-PbO) symmetry. The structural, electronic, vibrational and strain dependent properties are investigated by means of first principles calculations based on density functional theory. Our results demonstrate that monolayer α-CdTe is a dynamically stable and mechanically flexible material. It is found that the thinnest monolayer crystal of CdTe is a semiconductor with a direct band gap of 1.95 eV, which corresponds to red light in the visible spectrum. Moreover, it is found that the band gap can be tunable under biaxial strain. With its strain-controllable direct band gap within the visible spectrum, the stable α-phase of monolayer CdTe is a suitable candidate for optoelectronic device applications.