High-quality MgB2 thin films were obtained by pulsed laser deposition onto MgO or Al2O3 substrates, using differing methods. In the standard 2-step procedure, an amorphous precursor layer was deposited at room temperature; starting from the stoichiometric target and from the B target. It was then annealed in a Mg atmosphere in order to crystallize the superconducting phase. The resultant films exhibited a strong c-axis orientation, as revealed by XRD, a critical temperature of up to 38K and very high critical fields along the basal planes (up to 22T at 15K). An in situ one-step technique for the preparation of superconducting MgB2 thin films was also developed. In this case, the presence of an Ar buffer gas during deposition was crucial, and a strong dependence of the quality of the deposited film upon the background gas pressure was observed. The influence of the Ar atmosphere was confirmed by time- and space-resolved spectroscopic measurements of the emission spectrum of the plume. The Ar pressure strongly modified the plasma kinetics by promoting excitation and ionization of the plume species, especially of the most volatile Mg atoms; increasing their internal energy.

Growth Methods of c-Axis Oriented MgB2 Thin Films by Pulsed Laser Deposition. V.Ferrando, S.Amoruso, E.Bellingeri, R.Bruzzese, P.Manfrinetti, D.Marrè, R.Velotta, X.Wang, C.Ferdeghini: Superconductor Science and Technology, 2003, 16, 241-5