Superconducting MgB2 nanobridges and meanders obtained by an electron beam lithography-based technique ondifferent substrates

Abstract

In this work, we report on the fabrication and characterization ofMgB2 nanostructures on different substrates, namely silicon nitride and sapphire.Magnesium diboride films are fabricated by an all-in situ method consistingof the co-evaporation of B and Mg followed by in situ annealing at highertemperature. Samples thus obtained are characterized at low temperature and show aTc of about 34–38 K. The nanostructures are then defined by electron beam lithographycombined with physical etching (reactive plasma etching and ion milling).In this way, MgB2 nanostructures and meanders have been obtained with rather good electrical andtransport properties both on SiN and sapphire. The fabrication of superconductingMgB2 nanobridges on sapphire with a thickness of the order of a few tens of nanometersrepresents a step forward in the field of nanodevices, such as single-photon detectors, basedon this mid-temperature superconducting material.