Thickness dependence of the superconducting critical temperature in heavily doped Si:B epilayers

Audrey Grockowiak (1, 2) , Thierry Klein (1) , Hervé Cercellier (1) , Florence Lévy-Bertrand (1) , Xavier Blase (3) , J. Kacmarcik (4) , T. Kociniewski (5) , F. Chiodi (5) , D. Débarre (5) , G. Prudon (6) , C. Dubois (6) , C. Marcenat (2)

1 NEEL - MagSup - Magnétisme et Supraconductivité
2 SPSMS - UMR 9001 - Service de Physique Statistique, Magnétisme et Supraconductivité
3 NEEL - TMC - Théorie de la Matière Condensée
4 CLTP IEP - Centre of Low Temperature Physics
5 IEF - Institut d'électronique fondamentale
6 INL - DE - INL - Dispositifs Electroniques

We report on the superconducting properties of a series of heavily doped Si:B epilayers grown by gas immersion laser doping with boron content (nB) ranging from ∼3 × 1020 cm−3 to ∼6 × 1021cm−3 and thickness (d) varying between ∼20 nm and ∼210 nm. We show that superconductivity is only observed for nB values exceeding a threshold value (nc,S ) which scales as nc,S ∝ 1/d. The critical temperature (Tc) then rapidly increases with nB, largely exceeding the theoretical values which can be estimated by introducing the electron-phonon coupling constant (λe-ph) deduced from ab initio calculations into the McMillan equation. Surprisingly Tc(nB,d) is fully determined by the boron dose (nB × d) and can be well approximated by a simple Tc(nB,d) ≈ Tc,0[1 − A/(nB.d)] law, with Tc,0 ∼ 750 mK and A ∼ 8(±1) × 1015 cm−2.

Mots clés: supraconductivité

Domaines: Supraconductivité [cond-mat.supr-con]

Audrey Grockowiak, Thierry Klein, Hervé Cercellier, Florence Lévy-Bertrand, Xavier Blase, et al.. Thickness dependence of the superconducting critical temperature in heavily doped Si:B epilayers. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2013, 88, pp.064508. ⟨10.1103/PhysRevB.88.064508⟩. ⟨hal-00957153⟩