Two approaches to the in situ synthesis of superconducting MgB2 thin films were reported. In the first approach, Mg and B were simultaneously sputtered from 2 separate planar targets. The substrate temperature Ts was limited to 290–320C . The resulting films on sapphire substrates were c-axis textured with low growth quality. Their transition temperature TC reached a maximum of 24K with a transition width of 0.6K. A short-time in situ annealing at 600C raised TC to 28K. In the second approach, the Mg sputter source was replaced by a specially designed Mg evaporator. Due to this intense Mg source Ts could be increased to 440C , and TC of the “as-grown” films rose to 33K. Short-time in situ annealing after the film deposition enhanced TC to 36K. A high critical current density of 15MA/cm2 at 6K was also measured for these films.

In situ Deposition of MgB2 Thin Films by Magnetron Cosputtering and Sputtering Combined with Thermal Evaporation. R.Schneider, J.Geerk, G.Linker, F.Ratzel, A.G.Zaitsev, B.Obst: Physica C, 2005, 423[3-4], 89-95