Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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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.Conference Object Fabrication of Double Mesa Structures by E-Beam Lithography From High Temperature Superconducting Bi2sr2cacu2o 8+? (bi2212) for Powerful Terahertz Emission(Institute of Electrical and Electronics Engineers Inc., 2011) Demirhan, Yasemin; Türkoğlu, Fulya; Köseoğlu, Hasan; Minematsu, M.; Araki, H.; Miyakawa, Nobuaki; Özyüzer, LütfiWe work on a frequency tunable solid state device to meet the needs of continuous, coherent, powerful terahertz emission sources that fill practically important terahertz gap. High temperature superconducting (HTS) coherently oscillating Josephson junctions in Bi2Sr2CaCu 2O8+δ (Bi2212) crystal make this approach very promising. Since doping dependence of Bi2212 is an important parameter, Bi2212 crystals are annealed in vacuum or purified argon gas flow at 425°C. For further processing we pattern both single and double rectangular mesa structures by using electron beam lithography on the cleaved surface of the crystal. Resistance-temperature (R-T), and current-voltage behavior (I-V) measurements achieved. © 2011 IEEE.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.; Ploss, D.; Malzer, S.; Şimşek, Yılmaz; Wang, Huabing; Müller, P.Rectangular 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.