Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Book Part Citation - Scopus: 1Thz Sources and Detectors Fabricated From High Temperature Superconductors(Springer, 2021) Demirhan, Yasemin; Türkoğlu, Fulya; Altan, Hakan; Sabah, Cumali; Özyüzer, LütfiHigh temperature superconductors have unique properties that can be useful in the THz region, single crystal constituted from superconducting CuO2-layers could sustain high voltages across the junctions and they are coupled through the intrinsic Josephson Effect this maintains the potential for very intense, coherent radiation which spreads over the THz gap. We investigated various experimental techniques to fabricate THz sources, bolometers and filters for efficient THz emission and detection. Rectangular mesa structures were fabricated on Bi2Sr2CaCu2O8-x (Bi2212) single crystal superconductors using standard e-beam lithography and Ar ion beam etching systems and an emitted power as high as 60 ?W at frequencies up to 0.85 THz was detected from micron sized continuous wave terahertz sources. We also fabricated bolometric microchips for THz detection purpose from Bi2212 single crystals. Bi2212 microchips detected the signals and response time were calculated, our results have clearly shown that Bi2212 single crystals are potential candidates for THz detection. The detection properties and sensitivity of bolometer chips can be further improved by integrating an antenna and filter structures. In order to investigate this we have fabricated metamaterial THz filters based on metals and YBa2Cu3Ox superconducting thin films with metal-mesh shape and a unique fourcross shape pattern. Both a THz time domain spectrometer and a Fourier transform infrared spectrometer (FTIR) were used to investigate the performance of these filters and the results were compared with simulations done with a commercially available electromagnetic simulation software. © Springer Nature B.V. 2021.Conference Object Probing the Density of States of High Temperature Superconductors With Point Contact Tunneling Spectroscopy(Springer Verlag, 2005) Özyüzer, Lütfi; Zasadzinski, John F.; Miyakawa, Nobuaki; Gray, Kenneth E.Tunneling spectroscopy measurements are performed on single crystals of single CuO2 layer Tl2Ba2CuO6+delta, double CuO2 layer Bi2Sr2CaCu2O8+delta (Bi2212) and polycrystal quadruple CuO2 layer CuBa2Ca3Cu4O12+delta using the point contact tunneling technique. I-V and dI/dV-V characteristics are obtained at 4.2 K. In spite of different number of layers and T-c values, all three high-T-c superconductors exhibit similar spectral features including dip and hump features reminiscent of strong-coupling effects in conventional superconductors. The doping dependence of Bi2212 is studied and several effects of the hole concentration on spectral features are found. A novel effect is that the energy gap increases in the underdoped region even as T-c decreases. Combining the doping dependence of the energy gap and the dip energy provides additional information in order to understand the mechanism of high-T-c superconductivity. Point contact tunneling studies of the doping dependence of the energy gap in Bi2212 also helped to understand local variations of the gap magnitude observed by scanning tunneling microscopy, indicating that this type of spectroscopy is an integral part of the tunneling technique.Conference Object Citation - Scopus: 1Cleo®/Europe - Eqec 2015, an Indium Tin Oxide Metamaterial Filter for the Terahertz Regime: Design, Fabrication and Characterization(Optical Society of America (OSA), 2015) Takan, Taylan; Nebioğlu, Mehmet Ali; Kurt, Metin; Demirhan, Yasemin; Özyüzer, Lütfi; Sabah, Cumali; Altan, Hakan[No abstract available]