Multilayer Mg/NbO thin film nanostructures

Abstract

Multilayer (Mg/NbOx)82 nanostructures with different thickness of Mg layers and the constant thickness of NbOx layers have been prepared. The samples were obtained by ion-beam sputtering of metal and ceramic target and multiple consecutive depositions of NbOx and Mg layers onto substrates. The multilayering of the samples was confirmed by X-ray small-angle reflectometry. The thickness of one bilayer (magnesium layer + niobium oxide layer) was determined based on the small-angle data. The thickness of one bilayer in the studied structures was varied from 2.2 nm to 6.2 nm. Despite the separated deposition the magnesium layer's surface in the (Mg/NbOx)82 nanostructures was partially oxidized. The electric percolation transition was observed in the (Mg/NbOx)82 nanostructures at increase of the Mg layers thickness. At small bilayer thicknesses (less than 4.5 nm) the Mg phase is the partially oxidized nanogranules and the charge transfer in such samples is carried out by electron tunneling between the nanogranules. At larger bilayer thickness, the multilayer samples exhibit usual metallic conductivity.