WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Conference Object Spin Polarized Tunneling in Large Area Mesas of Superconducting Bi 2sr2cacu2o8+δ for the Generation of the Thz Waves(Institute of Electrical and Electronics Engineers Inc., 2009) Türkoğlu, Fulya; Şimşek, Yılmaz; Köseoğlu, Hasan; Demirhan, Yasemin; Meriç Polster, Zeynep; Özyüzer, LütfiRectangular intrinsic Josephson junction mesa structures of superconducting Bi2Sr2CaCu2O8+delta (Bi2212) can be used as a source of continuous, coherent and polarized terahertz (THz) radiation. THz emitting mesas are below a certain underdoped level of Bi2212. They have small Josephson critical current in contrast to optimally doped and overdoped Bi2212. We deposited Au/Co/Au multilayer top of mesa and obtained small critical current from mesas fabricated by as-grown Bi2212 single crystals due to injection of spin polarized current. The spin injection eliminates adjustment of doping level for successful THz emission.Conference Object Reactive Ion Beam Etching of Superconducting Bi2212 by Ta/Pr and Pr'/ta/pr Masks for the Generation of Thz Waves(Institute of Electrical and Electronics Engineers Inc., 2009) Köseoğlu, Hasan; Türkoğlu, Fulya; Demirhan, Yasemin; Meriç Polster, Zeynep; Özyüzer, LütfiGeneration of powerful THz radiation from intrinsic Josephson Junctions (Ills) of Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi2212) may require mesas with large lateral dimension. However, there are difficulties in fabrication of perfect rectangular mesas. Mesa lateral angles should be close to 90 degrees to obtain IJJs with same planar dimensions for synchronization of IJJs. Since thick photoresist (PR) layer shades the lateral dimension of mesa during ion beam etching, we patterned Ta/PR and PR'/Ta/PR masks on Bi2212 and used selective ion etching to overcome this problem. The reactive ion beam etchings have done with ion beam of Ar, N(2) and O(2) and we have obtained mesas about 1 mu m with lateral angle of approximately 50 to 75 degrees which is better than the mesas fabricated with single layer mask.