A photolithographic process, wherein a photosensitive layer is formed on a surface of a body to be defined; the photosensitive layer is exposed through a photolithographic mask having zones with lower transparency and zones with higher transparency so as to obtain exposed portions and shielded portions of the photosensitive layer; selective portions of the photosensitive layer chosen between the exposed portions and the shielded portions of the photosensitive layer are removed; and portions of the body under the selective portions of the photosensitive layer are selectively removed. The composite layer includes photoresist and carbon nanotubes, which are embedded in the photoresist and extend in a direction generally transverse to, and in electrical contact with, the body.