Simple methods of fabricating distinctive carbon nanotube networks with different growth density on the same substrate have been investigated. Special substrates fabricated by drying a tris-1,10-phenanthroline iron complex (ferroin) solution on a silicon substrate were used. The ferroin consisted of 1,10-phenanthroline and iron ions in solution. The dried ferroin solution formed fissure structures with unique shapes and iron particles that acted as catalysts for carbon nanotube growth on the substrates. Thermal chemical vapor deposition in a hydrogen-methane gas system was used to grow the carbon nanotubes. The density of the carbon nanotube networks was low in fissure areas and high in block areas. The results indicate that the dried ferroin solution not only produces distinctive carbon nanotube structures, but also changes the growth density on the same substrate. [DOI: 10.1380/ejssnt.2009.586]