Carbon nanotubes are unique nanostructures that are considered as one-dimensional (1D) quantum wires. The fundamental building block of carbon nanotube is very long. The word nanotube is derived from their size, because the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair) and can be up to several micrometers in length. A nanotube (also known as a buckytube) is a member of the fullerene structural family.