SKM 2021 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 1: Focus Session: Disordered and Granular Superconductors: Fundamentals and Applications in Quantum Technology I
TT 1.2: Talk
Monday, September 27, 2021, 10:30–10:45, H6
Superconducting silicon: material and devices — •Francesca Chiodi1, Pierre Bonnet1, Daniel Flanigan2, Raphaelle Delagrange1, Dominique Débarre1, and Hélène le Sueur2 — 1C2N, Université Paris-Saclay, CNRS, Palaiseau, France — 2SPEC, Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
Silicon is one of the most well-known materials, and the main actor in today electronics. Despite this, silicon superconductivity was only discovered in 2006 in laser doped Si:B samples. Laser annealing is instrumental to cross the superconductivity threshold, as the required doping is above the solubility limit, and cannot be reached using conventional micro-electronic techniques. Laser doping allows the realisation of epitaxial, homogeneous, thin silicon layers (5-300 nm) with extreme active doping as high as 11 at. %, and without the formation of B aggregates.
Silicon is a disordered superconductor, with a lower carrier density (1e20 to 5e21 cm-3) than metallic superconductors, a critical temperature modulable with doping from 0 to 0.8 K, and a relatively high resistivity that allows to easily match the devices to the void impedance.
We have realised microwave silicon resonators, working in the 1-12 GHz range and with quality factors about 4000. We have shown a strong non-linear response with power, observing a Kerr coefficient of the order of 300 Hz/photon where less than 1 Hz/photon was expected. To better understand the losses and recombination mechanisms, we have measured the relaxation dynamics of the resonators following a light or a microwave pulse.