Fabbricazione di stacks di giunzioni Josephson intrinseche da microcristalli di Bi-2212

THz radiation is presently of very large interest because of its many potential applications, from basic physics and chemistry to defence and communication, but all of them require powerful sources and suitable detection systems, which nowadays are not easily available yet. Among solid state THz radiation sources, one of the most interesting ones is represented by the intrinsic Josephson junctions in high temperature superconductors such as Bi-2212. In this case, a large number of synchronized junctions is required for high emission power, and a suitable technique that is being developed for such aim is X-ray nanopatterning: with this technique some trenches of non-superconducting material are introduced in the crystal by locally modifying the oxygen content of Bi-2212, in order to make the current flow through the Josephson junctions so that they can operate coherently and emit THz radiation. However, as a preliminary step, a reliable fabrication procedure of the samples is needed. The aim of this thesis is the development of such a procedure: a technique involving cleaving of Bi-2212 micro-crystals and fabrication of electrical contacts through photolithography and Ar etching is described. The electrical characterization of some successfully produced samples is also reported, along with the fabrication of trenches by means of Focused Ion Beam (FIB), which has resulted in the production of stacks of intrinsic Josephson junctions and in their characterization. Moreover, a novel procedure for the improvement of the thermal contact between the stacks of intrinsic Josephson junctions and the substrate has been investigated by means of low melting point alloys. In the future, all of these results will be exploited for the production of samples for X-ray nanopatterning and for the development of Bi-2212 based THz radiation sources.