The distribution of elements in MgB2 superconducting films prepared by sequential e-beam evaporation

The preparation of MgB2 superconducting films is often linked with difficulties to obtain the film stoichiometry due to the different melting points of deposited materials (magnesium and boron) and escape of Mg during in-situ annealing The interaction of the MgB2 films with an incident ion beam of the analytical technique applied can also be a problem, because it can cause distortion of the composition of the prepared films. Superconducting MgB2 thin films have been prepared on carbon substrates using sequential e-beam evaporation of boron and magnesium to create a multi-layer structure with a total thickness of 500 nm. After deposition, an in situ annealing was performed at 7000 C at various partial pressures of Ar. We studied the composition of the as-prepared and annealed films by ion beam analysis. The distribution of boron was measured by resonance nuclear reaction 11BΒ(ρ, γ)12 and the obtained results were confronted with Rutherford backscattering analysis and measurements of electrical properties. A possible influence of incident ion beam on the examined film is discussed. We showed that process of a sequential deposition of B and Mg followed by in-situ annealing is suitable for preparation of superconducting MgB2 (Authors)