Optoelectronic Properties of Carbon Nanotubes
Rice University, US
Keywords: optoelectronic, single-walled carbon nanotubes, SWNT
Abstract:This talk will describe optoelectronic possibilities of single-walled carbon nanotubes (SWNTs) based on our recent studies of optical, electro-optical, magneto-optical, and terahertz properties of SWNTs. Results will be discussed in terms of specific device applications, including light modulators, detectors, polarizers, and emitters. Because they have direct band gaps, SWNTs are a leading candidate to unify electronic and optical functionality in the same nanoscale circuitry. The past several years have witnessed remarkable progress in our understanding of light emission and absorption in SWNTs, revealing the unusual nature of one-dimensional excitons. While these pioneering studies have been performed in a weak-excitation, quasi-equilibrium regime, here we are strongly driving them to explore their optoelectronic potential under non-equilibrium conditions. Our nonlinear photoluminescence excitation spectroscopy study indicates that there is an upper limit in the density of excitons in carbon nanotubes due to very rapid and efficient exciton-exciton annihilation. Our transmission experiments in the presence of an electric field shows that a perpendicular field can modulate the absorption properties of SWNTs, similar to the quantum-confined Stark effect known to occur in semiconductor quantum wells. Finally, we have shown that aligned SWNTs act as a polarizer in the THz frequency range with an extremely large extinction ratio.