INITIAL GROWTH OF EPITAXIAL (001)SRTIO3 FILM DEPOSITED IN-SITU ON (001)YBACUO/(100)MGO

The surface morphology of both YBa2Cu3Oy (YBCO) thin film on a MgO substrate and SrTiO3 (STO) thin film on a YBCO film was observed using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) methods. These films were deposited by the ArF excimer laser deposition method. The c-axis-oriented YBCO film of 100 nm thickness grew spirally on a (100)MgO substrate in an island growth mode. The heteroepitaxial STO thin film deposited in situ on the YBCO film grew as if they had filled in the steps of the spiral structure of the YBCO thin film at the stage of initial growth, i.e., STO grew in a kink growth mode. The LEED pattern indicates that the film surface covered with STO was stable against ordinary air, although the thickness of STO thin film was about 1 nm.