Planar waveguides of organic material, mNA, which find many applications in the fields of integrated optics and optical communication were fabricated by using the modified Bridgeman method and the zone melting recrystallization method. The problems with the growing of single domain film were identified and discussed in relation with the growth conditions. The type and the geometry of spacer and the smoothness of a spacer edge are important factors for controlling the single crystal growth. Single crystalline film with a few domains could be obtained by using optimum growth conditions.