Microcavity-Controlled Chirality-Sorted Carbon Nanotube Film Infrared Light Emitters

Abstract

Applied as on-chip infrared light sources for future nanophotonic circuits and information optoelectronics, light emitters should show a narrow spectral width, strong emission, low onset voltage, and better tunability of light output to an external drive. Here, by utilizing small-diameter ( d < 1 nm) chirality-sorted (8,3) and (8,4) carbon nanotube (CNT) films and their charged exciton (trions) electroluminescence (EL), we achieve performance improvements via channel length ( L ch ) scaling. With a short L ch, the devices can show better emission, and the external EL efficiency (η EL ) in free space can reach ∼6 × 10 –4 (that is obtained at a current of ∼5–8 mA and a voltage of ∼4–6 V from the 0.5-μm-channel device, and the corresponding current density is ∼1700–3000 A cm –2 ). The strong emission at smaller bias gives CNT-based emitters a wider optoelectronic compatibility with other nanomaterial systems. Furthermore, by an integration of the emitter with a λ/2 optical cavity, cavity-controlled well-defined light output can be achieved, with narrow spectral widths at selectable emission windows (e.g., ∼28 meV at a wavelength of 1180 nm). The results show possible applications of chirality-sorted CNT film light emitters for further on-chip nanophotonic systems.