Method for making field-effect transistor using carbon nanotube

A method for making a field-effect transistor having source and drain electrodes and a gate in which current is controlled by varying conductivity of a channel functioning as a current path between the source and drain electrodes, the method comprising:

• forming a carbon nanotube thin film including semiconducting bare carbon nanotubes densely aligned on a first substrate in a direction intersecting a longitudinal direction of the carbon nanotubes;
• introducing a first functional group to a first end of each of the bare carbon nanotubes constituting the carbon nanotube thin film;
• attaching a second substrate onto a side of the carbon nanotube thin film opposite to the first substrate;
• removing the first substrate and introducing a second functional group to a second end of each of the bare carbon nanotubes;
• separating the carbon nanotube thin film from the second substrate and placing the carbon nanotube thin film in a solvent to disperse the carbon nanotubes having the first and second functional groups so as to prepare a dispersion;
• and
• applying the dispersion onto the source and drain electrodes composed of conductive materials that selectively interact with the first and second functional groups, the source and drain electrodes being formed in advance by patterning, so as to position the respective carbon nanotubes across the source and drain electrodes.