Improving Luttinger-liquid plasmons in carbon nanotubes by chemical doping

X. Tian, Q. Gu, J. Duan, R. Chen, H. Liu, Y. Hou and J. Chen

Nanoscale 10, 6288 (2018)
We realized the real-space imaging of Luttinger-liquid plasmons in semiconducting single-walled carbon nanotubes (s-SWCNTs) and studied the effects of chemical-doping-induced charge carrier density modulation on plasmons. Using scattering-type scanning near-field optical microscopy (s-SNOM), we compared the Luttinger-liquid plasmonic behavior in pre- and post-HNO3-doped SWCNTs. Raman measurements revealed that the physical mechanism is P-type doping. Through HNO3 doping, we effectively increased the charge carrier density in s-SWCNTs and achieved quantum plasmons simultaneously with strong confinement (l0⁄lp ≈ 70) and high quality factor (Q ≈ 20). The combination of high quality factor and strong subwavelength confinement in Luttinger-liquid plasmons is critical to the future application of plasmonic devices.