YBa 2Cu 3O 7- x thin films integrated on silicon-on-sapphire substrates with high critical current densities

Abstract

The deposition of YBCO thin films on buffer layered silicon-on-sapphire substrates was investigated. The critical current density of the superconducting thin films is 3.1 × 10 6 A cm -2 at 77 K. No degradation of j c with time on such substrates was observed after more than two months after the deposition. In contrast to thin films on pure silicon substrates, microcracks did not occur up to film thicknesses of 140 nm. The in-situ reduction of the SiO 2 during the initial stages of buffer growth and the subsurface re-oxidation of the silicon was investigated by XPS.