Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Köseoğlu, HasanSubject: search.filters.subject.Intrinsic Josephson junctions

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  • Article
    Citation - WoS: 12
    Citation - Scopus: 13
    Emission of the Thz Waves From Large Area Mesas of Superconducting Bi 2sr2cacu2o8+? by the Injection of Spin Polarized Current
    (Elsevier Ltd., 2013) Türkoğlu, Fulya; Özyüzer, Lütfi; Köseoğlu, Hasan; Demirhan, Yasemin; Preu, S.; Malzer, S.; Şimşek, Yılmaz; Wang, Huabing; Muller, P.
    Rectangular Au/Co/Au/Bi2Sr2CaCu2O 8+δ (Bi2212) mesa structures with large areas and high thicknesses were fabricated on as-grown Bi2212 single crystals in order to obtain small critical current from as-grown mesas by the injection of spin polarized current and so eliminate the adjustment of doping level for successful THz emission. We have performed c-axis resistance versus temperature (R-T), current-voltage (I-V) characteristics and bolometer measurements. It is the first time that THz emission has been observed from as-grown mesas due to injection of spin polarized current. © 2013 Elsevier Ltd. All rights reserved.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 26
    The Fabrication of Thz Emitting Mesas by Reactive Ion-Beam Etching of Superconducting Bi2212 With Multilayer Masks
    (Springer Verlag, 2011) Köseoğlu, Hasan; Türkoğlu, Fulya; Şimşek, Yılmaz; Özyüzer, Lütfi
    Generation of powerful THz radiation from intrinsic Josephson Junctions (IJJs) of Bi2Sr2CaCu2O8+δ (Bi2212) may require mesas with large lateral dimensions. However, there are difficulties in fabrication of perfect rectangular mesas. The lateral angles of mesas should be close to 90 degrees to obtain IJJs with same planar dimensions for synchronization of IJJs. We patterned Ta/photoresist and photoresist/Ta/photoresist masks on Bi2212 and used selectiveionetchingtoovercomethethickphotoresistlayershading on the lateral dimension of mesa during the ion-beam etching. The reactive ion-beam etchings have been done with ion beams of Ar, N2 and O2, and we have obtained mesas about 1 µm with lateral angle of approximately 50 to 75°, which is better than the mesas fabricated with photoresist mask.