Crystal engineering of oxide films in the fabrication of high-Tc Josephson tunnel junction

In relation to our research for the fabrication of high-Tc Josephson tunnel junction composed of YBCO(S)/oxide insulator(I)/YBCO layers, two crystal engineering issues are presented and discussed on pulsed laser processing of oxide thin films. One is the epitaxial growth of highly crystalline and orientation-controlled YBCO films and the other is the molecular layer epitaxy of perovskite and rock salt oxides films. Quantitative results are presented on the crystal quality, surface atomic layers and morphology, and electronic properties of the films and junctions. Discussion will be made on such problems as the thermodynamics versus kinetics in the film growth, identification and control of the topmost atomic layers of substrates and growing films, and electronic state of high-Tc films based on the scanning tunneling and photoelectron yield spectra.