Preparation of superconducting nanometer structures by means of scanning tunneling microscopy and of layer-by-layer MBE
- RWTH Aachen (Germany); and others
Thin films of YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) were patterned down to the sub-{micro}m scale by means of electron-beam lithography (EBL). A resist system based on amorphous carbon layers was developed, which allows the production of uncovered high-{Tc} superconductor microstructures. With this method the authors generated microbridges with a width of minimum 200 nm and a length of up to 5 {micro}m. The layered structure of high {Tc} superconductors enables a further modification of the microbridges on the nm-scale into lateral weak-links by means of a scanning tunneling microscope (STM) using high tunneling currents in the range of nA and fast scanning modes (etching). This modification was carried out in N{sub 2}-atmosphere after the YBCO microstructures were sputtered in Ne-atmosphere. In UHV they did not observe any etching process. Using atomic layer-by-layer MBE they have prepared BiSrCaCuO thin films and vertical S-N-S junctions on SrTiO{sub 3} substrates at 720 C in 2 {center_dot} 10{sup {minus}5} mbar ozone pressure. 40 nm thick Bi-2212 films showed an inductively measured {Tc} of 84 K. Thinner films have {Tc} values of 64 K and 46 K for 15 nm and 10 nm thick films, respectively. They present in-situ-STM images of the surface topography and TEM investigations of the dependence of the substrate/film interface on the first deposited layer. The S-N-S junction was made with Bi-2201 as barrier material and showed quasiparticle tunneling dI/dU-U characteristic. They estimated 2{Delta}(0)/k{sub B}{Tc} to 3.5--4 with a non BCS-like linear temperature dependence.
- Sponsoring Organization:
- Deutsche Forschungsgemeinschaft, Bonn (Germany)
- OSTI ID:
- 548479
- Report Number(s):
- CONF-960163-; ISBN 0-8194-2071-9; TRN: 98:000292
- Resource Relation:
- Conference: Photonics West `96: conference on quantum well and superlattice physics VI, San Jose, CA (United States), 27 Jan - 2 Feb 1996; Other Information: PBD: 1996; Related Information: Is Part Of Oxide superconductor physics and nano-engineering II; Bozovic, I. [ed.] [Varian Research Center, Palo Alto, CA (United States)]; Pavuna, D. [ed.] [Swiss Federal Inst. of Tech., Lausanne (Switzerland)]; PB: 578 p.; Proceedings/SPIE, Volume 2697
- Country of Publication:
- United States
- Language:
- English
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