Exciton Formation and Electroluminescence Quenching during 1D Impact Excitation of Carbon Nanotubes Field-Effect Transistors

There are few studies addressing the influence of excitonic effects on the electro-optical response of carbon nanotube (CNT) devices. We present here near infra-red electroluminescence (EL) from unipolar single- wall carbon nanotube field effect transistors (CNFETs) at high drain-source voltages. The conditions for emission at high field reveal that a single carrier type induces EL in CNFETs through a mechanism involving 1D impact excitation. Well-resolved spectra show that the emission is assigned to the radiative recombination of the E$_{1,1}$ exciton. An emission quenching is also observed at high field and attributed to an exciton-exciton annihilation process and free carrier generation. Excitons binding energy in the order of 270 meV for 1.4 nm CNTs is inferred from the spectral features..