MBE GROWTH OF INAS AND INSB ON EUBA2CU3O7-Y SUPERCONDUCTING FILMS

This paper reports, for the first time, on a low-temperature growth te chnique for obtaining crystalline InAs and InSb on a EuBa2Cu3O7-y (EBC O) film with a SrF2 interlayer preventing disruption of the underlying EBCO. Firstly, the InAs layer has been grown on the SrF2-coated EBCO by molecular beam epitaxy with a two-step growth procedure. An initial InAs layer was grown at room temperature with a thickness of more tha n 20 nm. A top InAs layer was then grown at 200-degrees-C. Consequentl y, (111) oriented crystalline InAs can be obtained by using this growt h process. Cross-sectional transmission electron microscopy (TEM) stud ies show that the SrF2 film completely covers the EBCO surface and tha t the interface between SrF2 and EBCO is very sharp. Secondly, InSb ha s been grown on SrF2-coated EBCO by a two-step process. Synchrotron-ra diation photoemission spectroscopy and X-ray photoemission spectroscop y studies demonstrate that InSb deposition reduces the amount of EBCO surface disruption as compared with InAs deposition. This is attribute d to the fact that InSb is more easily grown at lower temperatures tha n InAs. Furthermore, cross-sectional TEM analysis for an InSb-grown sa mple indicates that InSb deposition is promising for growing better ep itaxial layers on SrF2-coated EBCO.