A method of fabricating a carbon nanotube based device, including forming a trench having a bottom surface and sidewalls on a substrate, selectively depositing a bi-functional compound having two reactive moieties in the trench, wherein a first of the two reactive moieties selectively binds to the bottom surface, converting a second of the two reactive moieties to a diazonium salt; and reacting the diazonium salt with a dispersion of carbon nanotubes to form a carbon nanotube layer bound to the bottom surface of the trench.