AFM AND TEM STUDIES ON HIGH-QUALITY BI-2223 THIN-FILMS GROWN BY MOCVD

AFM and Tem observations of high-quality Bi-2223 thin films grown by M OCVD have been carried out to elucidate the crystal growth been carrie d out to elucidate the crystal growth mechanisms and the effect of sur face structures on superconducting properties. AFM images of the film surfaces grown on flat planes (off-angle<0.3 deg.) of LaAlO3, SrTiO3 a nd MgO (001) substrates showed a 2-dimensional nucleation growth . In contrast, those on vicinal (off-angle similar to 3 deg.) of LaAl03, Sr TiO3 and Nd:YalO3 (001) substrates showed a step flow growth. The film s grown on LaAlO3, SrTiO3 and Nd:AlO3 showed the highest Tc(0) of 97K reported for as-grown BSCCO films. In addition, a TEM plan-view image of the film grown on (001) LaAlO3 showed clearly the misfit dislocatio n network running along the orthogonal [110] directions at the heteroi nterface and having Burger's vectors b=1/2[110]. The clear AFM image o f regularly-shaped terrace or step-edge and the distinct TEM image of the misfit dislocation network are the evidence of high-quality MOCV g rown Bi-2223.