Combination of Yba2Cu307-6 with Semiconducting Substrates

Epitaxial YBa2Cu3O7-δ films were grown on silicon and gallium arsenide substrates. The common problem of strong interdiffusion at the elevated deposition temperatures could be solved employing appropriate buffer layers. In either case, however, there remain additional specific problems which severely affect the superconducting properties. On the one hand the large differential thermal expansion between silicon and YBa2Cu3O7_δ can lead to a fracture of thicker films. An investigation gave evidence that it is possible to further improve the fracture toughness of YBa2Cu307_δ films. On the other hand films on GaAs suffer from an arsenic contamination originating from the sides and the back of the wafer. This problem could be completely solved by a proper encapsulation yielding YBa2Cu307_δ films comparable to those on standard substrates.