Summary abstract: Growth, properties and applications of epitaxial YBa 2Cu 3O7− δ thin films on Si

Abstract

Earlier attempts to produce high quality thin films of YBa 2Cu 3 O 7− δ on Si substrates were thwarted by their reactivity and thermal expansion behavior. The collective research or several groups has demonstrated several epitaxial buffer layer systems including yttria-stabilized zirconia and MgO which allow the epitaxial growth of YBCO on Si without chemical reaction. Although direct epitaxy of YBCO on silicon may not be possible, buffer layers permit the growth of device quality YBCO films with critical current densities in excess of 10 6 A/cm 2 at 77 K. Methods have been developed to pattern these films in-situ by removing the buffer layer in selected areas to produce isolated superconducting mesas. The complications of thermally induced tensile stress have been eliminated through the use of silicon-on-sapphire instead of silicon. This work has revealed methods for controlling the in-plane epitaxy of YBCO films on zirconia via homoepitaxy and nucleation-initiating monolayers. A variety of application-oriented measurements and structures will be reported.