Growth of MgB2 thin films by means of in situ deposition techniques

We report on the growth of MgB2 thin films by means of Pulsed Laser Deposition (PLD) and Electron Beam (EB) deposition techniques. In order to develop an in-situ deposition procedure both techniques have been exploited following two approaches: the "as grown" procedure, where the superconducting phase is formed during the film growth, and no further process is performed, and the "annealing" procedure, where precursor layers are deposited and annealed in argon atmosphere. In the case of EB evaporated films, the "as grown" procedure revealed to be inadequate, because of the low reactivity of the thermally evaporated species and the high magnesium volatility. On the contrary, using PLD, the higher reactivity of the plasma species promotes the formation of the superconducting phase at deposition temperature as low as 350degreesC. In the "annealing" procedure, different kinds of precursor layers have been studied, in order to reduce and prevent the fast Mg evaporation at high temperature. Different annealing processes were investigated in order to promote the interdiffusion and reaction between Mg and B. The films were characterised by means of resistivity measurements and X-ray analyses. The surface morphology was observed by SEM microscopy.