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TT: Fachverband Tiefe Temperaturen

TT 30: Superconductivity - Poster Session

TT 30.18: Poster

Montag, 31. März 2014, 15:00–19:00, P2

Doping-induced superconductivity in germanium — •M. Naumann, R. Skrotzki, T. Herrmannsdörfer, R. Schönemann, V. Heera, J. Fiedler, M. Voelskow, A. Mücklich, B. Schmidt, W. Skorupa, M. Helm, and J. Wosnitza — Hochfeld-Magnetlabor Dresden (HLD) und Institut für Ionenstrahlphysik und Materialforschung, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), P.O. Box 51 01 19, D-01314 Dresden, Germany

We report observations of superconductivity in highly doped germanium. High dopant concentrations of Al, B, Ga, In, Nb, P, or Sn have been introduced into nanolayers of Ge wafers via ion implantation. The electrical-transport properties of these thin-film samples strongly depend on the element type of dopant atoms, implantation dose, and on subsequent short-term annealing procedures. For Ge:Ga and Ge:In, we observe the emergence of superconductivity for certain sample-preparation conditions. In particular, the occurence of superconductivity requires well balanced flash-lamp or rapid thermal annealing conditions. On the one hand, the local temperature increase during annealing needs to be sufficiently intense to effectively activate dopant atoms as charge carriers. On the other hand, overheating and entire separation of dopant atoms in the germanium matrix needs to be avoided. Most likely, the superconducting state in highly doped germanium is triggered in dopant rich nano clusters and streched over their entire thin-film zone through percolation, tunneling, or proximity-effect networks.