Probing the unique electrical and optical properties in one-dimensional carbon nanotubes and nanoribbons

摘要

Electrons confined in one-dimension (1D) show distinct behavior from their higher-dimensional counterparts:these con-fined electrons form a strongly correlated system described by a Luttinger liquid which exhibits a unique power-law decay of correlation functions and spin-charge separation;they exhibit divergence in the density of states (DOS) known as a van Hove singularity. 1D quantum conductor such as metallic single-walled carbon nanotubes (SWNTs) has provided a rich play-ground to explore the Luttinger liquid physics featuring the power-law decay of electron tunneling probability and plasmons excitation and propagation with remarkable spatial confinement of the optical field. On the other hand, 1D quantum semi-conductor such as semiconducting SWNTs and atomically precise graphene nanoribbons (GNRs) has revealed the extremely strong excitonic effect and polarization sensitivity spanning the entire UV-vis-NIR spectral range, making it attractive in the study of fundamental science and optoelectronic applications. In this talk, I will describe our recent effort in probing the interesting 1D physics in SWNTs and atomically precise arm-chair GNRs (AGNRs) [1-3]. We have combined the electron tunneling spectroscopy and scanning near-field optical nanos-copy to carry out an ultimate experimental test of Luttinger liquid theory in the unique junctions formed by two crossed SWNTs. We have also observed the sequential band-to-band resonant tunneling processes over a large spectral window (~2 eV) by electron tunneling spectroscopy, which was realized in the unique carbon nanotube/hexagonal boron nitride/carbon nanotube heterojunctions. A polarization spectroscopy technique in the visible and near-IR has been successfully employed to measure the optical absorption spectra of 7-AGNRs and 9-AGNRs that were transferred onto an insulating substrate, whose optical bandgaps agree well with the GW-BSE calculated results. If time allows, I will also discuss the unique oppor-tunity that the combined electrical and optical probes promise in the experimental exploration of exotic physical phenome-non in two-dimensional materials.