A method of forming a plurality of nanotubes is disclosed. Particularly, a substrate may be provided and a plurality of recesses may be formed therein. Further, a plurality of nanotubes may be formed generally within each of the plurality of recesses and the plurality of nanotubes may be substantially surrounded with a supporting material. Additionally, at least some of the plurality of nanotubes may be selectively shortened and at least a portion of the at least some of the plurality of nanotubes may be functionalized. Methods for forming semiconductor structures intermediate structures, and semiconductor devices are disclosed. An intermediate structure, intermediate semiconductor structure, and a system including nanotube structures are also disclosed.