Short-wavelength electroluminescence (EL) emission is observed from unipolar and ambipolar carbon nanotube field-effect transistors (CNFETs) under high bias voltage. EL measurements were carried out with an unsuspended single-walled carbon nanotube (SWNT) in high vacuum to prevent the oxidation damage induced by current heating. Short-wavelength emission under high bias voltage is obtained because of the Schottky barrier reduction and the electric field increase in a SWNT. The simultaneous measurements of transport and EL spectra revealed the excitation mechanism of impact excitation or electron and hole injection dependent on the conduction type of unipolar or ambipolar characteristics. In addition to the EL emission, blackbody radiation was also observed in a p-type CNFET. Taking into account the device temperature estimated from blackbody radiation, the contribution of impact excitation and thermal effect to the exciton production rate was evaluated.
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