Photonics / Fotonik

Permanent URI for this collectionhttps://hdl.handle.net/11147/2590

Browse

Filters

2018 - 201942020 - 20221

Settings

Language: search.filters.language.enScopus Q: search.filters.scopusQuartile.N/A

Search Results

Now showing 1 - 5 of 5
  • Preprint
    Electronic, Magnetic and Vibrational Properties of Single Layer Aluminum Oxide
    (2022) Özyurt, A. Kutay; Molavali, Deniz; Şahin, Hasan
    The structural, magnetic, vibrational and electronic properties of single layer aluminum oxide (AlO2) are investigated by performing state-of-the-art first-principles calculations. Total energy optimization and phonon calculations reveal that aluminum oxide forms a distorted octahedral structure (1T'-AlO2) in its single layer limit. It is also shown that surfaces of 1T'-AlO2 display magnetic behavior originating from the O atoms. While the ferromagnetic (FM) state is the most favorable magnetic order for 1T'-AlO2, transformation to a dynamically stable antiferromagnetic (AFM) state upon a slight distortion in the crystal structure is also possible. It is also shown that Raman activities (350-400 cm^-1) obtained from the vibrational spectrum can be utilized to distinguish the possible magnetic phases of the crystal structure. Electronically, both FM and the AFM phases are semiconductors with an indirect band gap and they can form a type-III vdW heterojunction with graphene-like ultra-thin materials. Moreover, it is predicted that presence of oxygen defects that inevitably occur during synthesis and production do not alter the magnetic state, even at high vacancy density. Apparently, ultra-thin 1T'-AlO2 with its stable crystal structure, semiconducting nature and robust magnetic state is a quite promising material for nanoscale device applications.
  • Article
    Single Layer Res2h2: Stability, Raman Activity and Electronic Properties
    (Eskişehir Teknik Üniversitesi, 2018) Ünsal, Elif; Şahin, Hasan
    In this study, the structural, vibrational and electronic properties of the hydrogenated single layer of ReS2 are investigated byperforming the first principle calculations based on density functional theory. We found that the characteristic properties ofthe monolayer ReS2 can be manipulated upon the hydrogen functionalization. As the monolayer ReS2, the ReS2H2 hasdistorted 1T phase; however, the bonding in Re slab significantly varies with the hydrogenation. Our results demonstrate thatthe full-surface hydrogenation leads to an expansion in lattice and the Re4 tetramer-chains in the monolayer ReS2 areseparated into two dimers in the hydrogenated monolayer. It is calculated that the dynamically stable monolayer of ReS2H2has 26 Raman-active vibrational modes. Constant volume specific heat calculations are also performed and the resultsindicate that at high temperature, the monolayer ReS2 approaches to limit of 3R before the monolayer ReS2H2. By performingthe electronic band structure calculations, it is shown that when the ReS2 surface is fully hydrogenated, there occurs a directto indirect band gap transition and the semiconducting hydrogen-induced monolayer has a band gap of 0.74 eV.
  • Patent
    Silicon-Based Emitter Compound
    (Espacenet, 2018)
    The present invention relates to emitter compounds E of formula or salts thereof based on a triazine core, substituted with at least one moiety of formula: and at least one donor moiety. Further, the present invention also refers to a light-emitting layer B comprising the emitter compound E and to an opto-electronic device OD comprising such light-emitting layer B. Moreover, the present invention relates to a method for generating light of a desired wavelength range by means of the opto-electronic device OD.
  • Conference Object
    Reversible Energy Transfer Between a Single Defect in Hbn and Graphene
    (OSA - The Optical Society, 2019) Özçeri, Elif; Arı, Ozan; Balcı, Sinan; Kocabaş, Coşkun; Ateş, Serkan
    We present a reversible energy transfer between a single defect in hBN and graphene. Dynamic control of Fermi level of graphene results in switching on and off single photon emission from a single quantum emitter. © OSA 2019 © 2019 The Author(s)
  • Conference Object
    Citation - WoS: 3
    Citation - Scopus: 2
    Fabrication and Characterization of a Solution Processed Flexible Thermal Sensor by Using Chemically Synthesized Go and Rgo
    (Institute of Electrical and Electronics Engineers Inc., 2019) Bozkurt, Hakan; Diker, Halide; Varlıklı, Canan
    Graphene oxide (GO) was reduced by ascorbic acid which is an environmental-friendly reductant and obtained sample was named as reduced GO (rGO). Stable dispersions of GO and rGO were prepared in N,N-Dimethylformamide (DMF). Compared to GO sample, rGO was determined to have more thermal stability, smaller sheet size and lower surface energy. GO and rGO dispersions were drop-casted on aluminum (Al) coated acetate substrate and used as thermal sensor. Fabricated sensors were tested from 25 °C to 150 °C. The sensors fabricated with GO, were not stabile against driven temperature changes. However, rGO ones, presented no thermal hysteresis effect after the first heating step. This sensor (Al/rGO/Al) acted like an NTC (Negative Temperature Coefficient) thermistor. The resistance of the rGO sensor was changed between 42 k? to 25 k? depending on the test temperature range (25 °C to 150 °C). Average beta value was calculated as 519.7649 K. © 2019 IEEE.