Hot carrier electroluminescence from a single carbon nanotube

We measure the spectrum and efficiency of the infrared light emission from ambipolar carbon nanotube field-effect transistors. The width of the emission peak is strongly device-structure dependent. Long devices (∼50 μm) show narrow spectral peaks that we attribute to relaxed carrier recombination, while short devices (∼500 nm) show broad peaks due to hot carrier recombination. The hot carrier distribution is limited to energies below the energies of the optical/zone boundary phonons near 180 meV. The efficiency of the radiative recombination is between 10-6 and 10-7 photons/electron-hole pair, and the possible quenching mechanisms are discussed.