Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Article Citation - WoS: 12Citation - Scopus: 13Emission 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; Özyüzer, Lütfi; Demirhan, Yasemin; Preu, S.; Demirhan, Yasemin; Şimşek, Yılmaz; Wang, Huabing; Muller, P.; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyRectangular 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.Conference Object Terahertz Wave Emission From Layered Superconductors: Interferometer Measurements(Institute of Electrical and Electronics Engineers Inc., 2011) Özyüzer, Lütfi; Türkoğlu, Fulya; Demirhan, Yasemin; Köseoğlu, Hasan; Preu, S.; Özyüzer, Lütfi; Malzer, S.; Şimşek, Yılmaz; Wang, Huabing; Müller, P.; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyRectangular Bi2Sr2CaCu2O 8+δ (Bi2212) mesa structures were fabricated on as-grown Bi2212 single crystal superconductors using standard photolithography and Ar ion beam etching techniques. We have performed c-axis resistance versus temperature (R-T), current-voltage (I-V) characteristics and bolometer measurements. Furthermore, in contrast to previous studies, the emission frequency was determined using interferometer set up instead of FTIR. The interference patterns were detected outside the cryostat after traveling long way through ambient space. The emission frequency calculated by Fourier transform of interference data is consistent with Josephson frequency-voltage relation. © 2011 IEEE.Article Citation - WoS: 24Citation - Scopus: 26The Fabrication of Thz Emitting Mesas by Reactive Ion-Beam Etching of Superconducting Bi2212 With Multilayer Masks(Springer Verlag, 2011) Köseoğlu, Hasan; Türkoğlu, Fulya; Özyüzer, Lütfi; Özyüzer, Lütfi; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyGeneration 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.Article Citation - WoS: 40Citation - Scopus: 45Terahertz Wave Emission From Intrinsic Josephson Junctions in High- Tc Superconductors(IOP Publishing Ltd., 2009) Özyüzer, Lütfi; Şimşek, Yılmaz; Özyüzer, Lütfi; Türkoğlu, Fulya; Kurter, Cihan; Welp, U.; Koshelev, A. E.; Gray, Kenneth E.; Kwok, W. K.; Yamamoto, T.; Kadowaki, K.; Koval, Yu I.; Wang, Huabing; Müller, Paul H.; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyRecently, we experimentally demonstrated that rectangular mesa structures of intrinsic Josephson junctions (IJJ) in Bi2Sr2CaCu 2O8+d (Bi2212) can be used as a compact solid-state generator of continuous, coherent and polarized terahertz (THz) radiation. In the present work, we will exhibit tall mesas (over 600 junctions) which were fabricated using UV lithography, e-beam lithography with photoresist and e-beam lithography with a Ti selective etching technique. We will present measurements of the c-axis resistance as a function of temperature and of current-voltage characteristics of THz emitting mesas with lateral sizes ranging from 30 × 300 to 100 × 300νm2. Furthermore, we will discuss the dependence of the characteristics of the mesa structures on the oxygen doping level of the Bi2212 crystals. We will also experimentally show that the voltage-frequency relation of the ac Josephson effect has to match the cavity resonance for successful emission.