Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 5: Postersession Superconductivity: Materials - Fabrication and Properties
TT 5.1: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
Superconductivity in Ga-doped Germanium — •R. Skrotzki1, T. Herrmannsdörfer1, V. Heera2, O. Ignatchik1, M. Uhlarz1, A. Mücklich2, M. Posselt2, H. Reuther2, B. Schmidt2, K.-H. Heinig2, W. Skorupa2, M. Voelskow2, C. Wündisch2, and J. Wosnitza1 — 1Hochfeld-Magnetlabor Dresden, Forschungszentrum Dresden-Rossendorf (FZD) — 2Institut für Ionenstrahlphyik und Materialforschung, FZD
We report the first observation of superconductivity in heavily p-type doped germanium at ambient pressure conditions. Using Ga as dopant, we have produced a series of Ge:Ga samples by ion-beam implantation and subsequent short-term (msec) flash-lamp annealing. The combination of these techniques allows for Ga concentrations up to 6%, i.e., a doping level which is clearly larger than the solubility limit and not accessible to any other method so far. Transport measurements reveal superconducting transitions with Tc up to 0.5 K. In more detail, we observe a strong dependence of the superconducting critical parameters on the annealing conditions. Further, we find a strong anisotropy of the superconducting critical field reflecting the two-dimensional character of the superconducting state in the thin Ge:Ga layer having an effective depth of only 60 nm. We find critical magnetic in-plane fields even larger than the Pauli-Clogston limit. After its finding in Si [1] and diamond [2], our work reports another unexpected obervation of superconductivity in doped elemental semiconductors.
[1] E. Bustarret et al., Nature 444, 465 (2006).
[2] E. A. Ekimov et al., Nature 428, 542 (2004).