Superconducting MgB2nanobridges and meanders obtained by an electron beam lithography-based technique on different substrates

In this work, we report on the fabrication and characterization of MgB2 nanostructures on different substrates, namely silicon nitride and sapphire. Magnesium diboride films are fabricated by an all-in situ method consisting of the co-evaporation of B and Mg followed by in situ annealing at higher temperature. Samples thus obtained are characterized at low temperature and show a Tc of about 34–38 K. The nanostructures are then defined by electron beam lithography combined with physical etching (reactive plasma etching and ion milling). In this way, MgB2 nanostructures and meanders have been obtained with rather good electrical and transport properties both on SiN and sapphire. The fabrication of superconducting MgB2 nanobridges on sapphire with a thickness of the order of a few tens of nanometers represents a step forward in the field of nanodevices, such as single-photon detectors, based on this mid-temperature superconducting material.