In an embodiment, a method includes liberating feed atoms and forming at least one nanotube from the liberated feed atoms. Feed atoms disposed over a front side of a substrate are liberated in response to electromagnetic radiation that propagates from the back side of the substrate, through the substrate, to the front side of the substrate. And, from the liberated feed atoms, at least one nanotube is formed over the front side of the substrate in response to at least one catalyst separate from the substrate and disposed over the front side of the substrate and over the feed atoms.