Superconducting very thin films (3-8 nm) of cubic B1 nitrides such as TiN, Nb(1-x)TixN or NbN have been achieved in "Hot Electron Bolometer" (HEB) nanostructures or in thin vertical tunnel devices. Very thin layers epitaxially grown, smooth and sharp interfaces are required in order to best benefit from fast ballistic and out of thermal equilibrium effects involving quasi-particles injected or photon generated inside the superconductor. R-plane Sapphire (up to 3 inch) and (100) MgO substrates have been selected for their large gap and good mechanical, microwave, infrared and surface properties. Films are DC-MAG sputtered from metal targets in a reactive mixture of nitrogen and argon gas, on substrate heated up to 650C. As example, 4.5 nm NbN films covered by a 1.5 nm AlN passivation layer, has a Tc=11 K with a large critical current density at 4.2 K (> 1MA/cm2) and HC2 > 14 Tesla at 1K. Such ultra-thin films undergo a superconducting-insulator transition at low temperature which can be tuned by a magnetic field or by quasi-particle injection (spin polarized or not) opening new physical effects as well applications. Optical transmission and energy gap topography are done by LT-STM, AFM, grazing angle XRD and ellipsometry.
We will describe nanostructuration of fast single photon detectors (SSPD) and THz HEB mixers, by electron beam lithography and reactive ion etching: a 10 µm square pixel has a filling factor > 0.5 with 150 nm wide stripes. IR photon counting at 4 K will be presented at high rates (>10 GHz), with a quantum efficiency suitable for quantum optics and astronomical applications. Spin-injection or Rapid Single Flux Quantum logic circuits can also benefit from LTS and HTS nanostructures: ICM sputter grown 10-30 nm thick YBa2Cu3O7- HEB mixers have been patterned on MgO with Tc > 85K and recently Hg(1-x)Re(x)Ba2Ca(n-1)Cu(n)O(2n+2+) on LAO and MgO with n= 2 and n=3 is showing Tc up to 130 K.

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