In-situ observation and surface morphology of YBa 2 Cu 3 O 7-y films by metalorganic chemical vapor deposition

YBa2Cu3O7 thin films were prepared on single-crystalline substrates by metalorganic chemical vapor deposition (MOCVD) with liquid sources. We investigated surface morphology of the samples by atomic force microscopy (AFM), and found the abrupt change in the terrace width and the supersaturation ratio at the deposition temperature of around 750°C. We suggest the appearance of a quasi-liquid on the growing crystal surface and this transition temperature corresponds to the growth change from the conventional vapor growth to the VLS (vapor-liquid-solid) growth. Furthermore, we prepared and characterized the YBCO films grown by a novel growth method using VLS mode. The growth rate of the films using VLS mode is about five times as large as the growth rate using the conventional growth.