Ag–B Thin Films Prepared by Magnetron Sputtering

Abstract

ABSTRACTThe discovery of the new superconductor MgB2 with critical temperature of Tc = 39 K stimulated great activity in search for materials with higher Tc. Theoretical works predicted the possibility of obtaining such superconducting materials in other borides also, in particular in AgB2. It was predicted in these works that diborides of metals having the AlB2 type structure, among them AgB2 may have superconductivity with a Tc higher than 39 K. In an early very short report the lattice parameters of AgB2 were evaluated in a synthesized specimen. However, no other indication exists that AgB2 was ever produced. We report the preliminary results of our attempts to prepare AgB2 films.Thin films of Ag-B were produced by magnetron cosputtering in Ar ambient from two separate targets that of B and Ag on Si (100) substrates. The specimens were subjected to X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photo spectroscopy (XPS), Auger analysis and optical microscope (OM) investigations. Resistivity measurements in a wide temperature range were measured. No superconductivity was yet observed in the range ∼10 – 200. K on the basis of resistivity measurements. Preliminary results indicate that AgB2 might be an unstable phase.