INITIAL GROWTH MECHANISM OF YBa2Cu3Oy CRYSTAL ON MgO SUBSTRATE BY LIQUID-PHASE EPITAXY

Initial growth features of YBa2Cu3Oy (YBCO) crystal on an MgO substrate by a liquid phase epitaxy (LPE) process were investigated and compared with homoepitaxial growth on a YBCO substrate. The partial dissolution of the seed grains in the initial stage of the LPE growth was influenced by the crystallinity of in-plane alignment of the seed grains, which can be explained by the preferential dissolution and growth mechanism. Concurrently, the slope angle of the growth grain varied with growth time. The opposite tendency of the slope angle change between the hetero- and the homoepitaxial growth was observed and can be explained by considering the difference in the step-advancing rates on each interface. It is understood that the formation of entrapped liquid inclusions was a combination of both the small step-advancing rate of YBCO crystals on the MgO surface and the roughening of the MgO surface due to the partial dissolution of MgO. 29 refs.