Structural investigations of superconducting multilayers consisting of semiconducting materials

There are rather exotic semiconductor superlattices (SL) consisting of mono chalcogenides of Pb, Sn, and rare-earth metals which exhibit superconductiv ity at temperature as high as 6 K. Here we report the results of precision x-ray diffractometry and TEM investigations as well as Auger spectroscopy d ata obtained on some of the epitaxially grown superconducting semiconductor SLs. It is established that the essential features of the SL structure det ermining the appearance of superconductivity are the perfect single-crystal linity of the samples and the presence of continuous dense grids of misfit dislocations on the interfaces between two semiconductors. The segregation of free Pb which was observed in some cases does not correlate, according t o experimental data, with the appearance of superconductivity. (C) 2001 Ame rican Institute of Physics.