I-V, V-Phi characteristics and atomic force images of grain boundary Joseph
son junctions fabricated on SrTiO3, bicrystal substrates were investigated.
The half integer Shapiro steps and I, versus B curves show evidence of the
inhomogeneous current distribution along the grain boundary junction, The
de SQUID formed on the grain boundary shows the expected V-Phi curve. The A
FM images, R-T curves and IcRn product reveal sequential destructive deteri
oration of the junction originating from the underlying grooved substrate,
The results are discussed.