Single and double spiral growth of C60 epitaxial films on a KBr (001) substrate were observed via atomic force microscopy. Single and double spirals were found on films grown at different rates. All of the spiral islands exhibited the 3-fold symmetry of the face-centered cubic structure. In the case of single spirals, many fringes were observed in 3 equivalent [1¯10] directions on the face-centered cubic (111) surface. On the basis of the atomic force microscopy images, it was concluded that the growth of these spirals could be explained in terms of the Burton-Cabrera-Frank crystal growth theory, and that screw dislocations formed without any direct influence of the substrate.

Y.Kim, L.Jiang, T.Iyoda, K.Hashimoto, A.Fujishima: Applied Physics Letters, 1997, 71[24], 3489-91