The effects of annealing upon the grain boundary of a 36.8º symmetrical [100] tilt bicrystal were studied. Scanning tunnelling microscopy and atomic force microscopy were used for the non-destructive observation of boundary structures. It was found that annealing the bicrystalline substrates at temperatures as low as 780C led to the formation of grooves at their boundaries. This provided direct evidence that the thickness depression of Cu3Ba2YO7 films at the bicrystal boundaries originated from the underlying grooved substrates. Hole-like defects, with diameters ranging from some 30 to 200nm, were also observed.

O.D.Jiang, Z.J.Huang, A.Brazdeikis, M.Dezaneti, C.L.Chen, P.Jin, C.W.Chu: Applied Physics Letters, 1998, 72[25], 3365-7