Condensed Matter Seminar
January 8, 2018 -
3:00pm to 4:00pm
Howey, Room N110
Los Alamos National Laboratory-Theoretical Division
Semiconductor single-walled carbon nanotubes (CNTs) are near-perfect 1D materials with great potential for applications in opto-electronic and photonic devices. Their unique optical properties are determined by highly mobile interacting excitons (bound electron-hole states). Motivated by experiment, we examine competition between exciton diffusion dynamics and their local interactions resulting in the exciton-exciton annihilation.
Our model explains experimentally observed dependence of the exciton emission profile on the intensity of the optical pump and further allows us to interpret measured photon counting statistics (i.e., the 2nd order photon number correlation function). To have an insight into sharp anomalous features observed in Raman excitation profiles of radial breathing and G-mode in high purity (6,5) CNT bundles, we assume formation of intertube exciton states and develop a scattering model for their scattering by the intratube states. Our analysis shows that the scattering of bright intratube exciton by dark intertube exciton whose resonance response overlap results in the formation of Fano resonance that we attribute to the observed anomalous peak. Furthermore, the universality of the model suggests that similar Raman excitation profile features may be observed in interlayer exciton resonances in 2D multilayered systems.