Optoelectronic Properties of Single‐Wall Carbon Nanotubes

Abstract

Single-wall carbon nanotubes (SWCNTs), with their uniquely simple crystal structures and chirality-dependent electronic and vibrational states, provide an ideal laboratory for the exploration of novel 1D physics, as well as quantum engineered architectures for applications in optoelectronics. This article provides an overview of recent progress in optical studies of SWCNTs. In particular, recent progress in post-growth separation methods allows different species of SWCNTs to be sorted out in bulk quantities according to their diameters, chiralities, and electronic types, enabling studies of (n,m)-dependent properties using standard macroscopic characterization measurements. Here, a review is presented of recent optical studies of samples enriched in 'armchair' (n = m) species, which are truly metallic nanotubes but show excitonic interband absorption. Furthermore, it is shown that intense ultrashort optical pulses can induce ultrafast bandgap oscillations in SWCNTs, via the generation of coherent phonons, which in turn modulate the transmission of a delayed probe pulse. Combined with pulse-shaping techniques, coherent phonon spectroscopy provides a powerful method for studying exciton-phonon coupling in SWCNTs in a chirality-selective manner. Finally, some of the basic properties of highly aligned SWCNT films are highlighted, which are particularly well-suited for optoelectronic applications including terahertz polarizers with nearly perfect extinction ratios and broadband photodetectors.

Ultrafast Generation of Fundamental and Multiple-Order Phonon Excitations in Highly Enriched (6,5) Single-Wall Carbon Nanotubes

“…These values are in good agreement with those reported for other studies of (6,5) SWCNTs. 19 The other smaller features are due to the phonon sidebands of the E 11 and E 22 peaks as well as higher-order (E 33 , E 44 , etc.) interband transitions in the shortest wavelength region of the spectrum.…”

“…[9][10][11][12][13][14] While many of the features in prior studies were obscured due to the many different chiralities present in the samples, in highly-enriched samples these features are better resolved, allowing one to study the intrinsic behaviors of one-dimensional (1-D) electrons, phonons, and excitons in SWCNTs in far greater detail. Moreover, the availability of highly-purified singlechirality SWCNTs opens up new possibilities for the development of optoelectronic devices [15][16][17][18][19] that are useful for optical communications, spectroscopy, imaging, and sensing.…”

Fundamental optical processes in armchair carbon nanotubes

“…The combined data sets of tabulated (n, m) with RBM frequencies and optical transition energies allowed Maultzsch et al 97 and also Jorio et al 99 to develop empirical equations to predict both RBM frequencies and optical transition energies for nanotubes, which has served as an experimental predictive tool for locating previously unobserved spectral features. 100 Jorio et al, 99 in particular, attempted to take existing expressions for tight-binding calculations predicting SWCNT optical transitions and add additional chiral-angle-dependent and logarithmic terms to account for chiral-dependent electron and hole effective masses and many-body corrections, respectively, with parameters tuned to fit existing optical data.…”

Theory of coherent phonons in carbon nanotubes and graphene nanoribbons

“…The optoelectronic properties and characterization of SWNTs have been reviewed from an experimental perspective in the excellent article by Nanot et al in [48]. There they discuss the experimental generation and detection of coherent phonons using CP spectroscopy and compare the results of CP spectroscopy with resonant Raman spectroscopy (RRS) and photoluminescence excitation (PLE) spectroscopy.…”