Mobile ambipolar domain in carbon-nanotube infrared emitters

The spatial resolution of infrared light emission from ambipolar carbon-nanotube field-effect transistors (CNTFET), was analyzed. The injection of electrons and holes was performed from opposite contacts into a single nanotube molecule. It was observed that ambipolar domain formed a microscopic light emitter within carbon nanotube. The additional stationary spots appeared due to defect-assisted Zener tunneling or impact ionization, at high electric fields. The results show that light carrier generation sites could also be identified, while analysis of shape of light spot provides information on recombination length.