Spatially resolved scanning tunneling spectroscopy on single-walled carbon nanotubes

Abstract

Scanning tunneling microscope spectroscopy is used to study in detail the electronic band structure of carbon nanotubes as well as to locally investigate electronic features of interesting topological sites such as nanotube ends and bends. From a large number of measurements of the tunneling density-of-states ͑DOS͒ nanotubes can be classified, according to predictions, as either semiconducting ͑two-third of the total number of tubes͒ or metallic ͑one-third͒. The energy subband separations in the tunneling DOS compare reasonably well to theoretical calculations. At nanotube ends, spatially resolved spectra show additional sharp conductance peaks that shift in energy as a function of position. Spectroscopy measurements on a nanotube kink suggest that the kink is a heterojunction between a semiconducting and a metallic nanotube.

Transfer doping of a metallic carbon nanotube and graphene on metal surfaces

“…1). The predicted p-type doping of a metallic nanotube on a Au(111) surface is consistent with experiments, 9,12,13 although the predicted Fermi-level shift, E F = 0.14 eV, is somewhat smaller than the experimental values, E F ≈ 0.20−30 eV. Figure 5 shows the DFT calculations for the Fermi-level shifts E F of the nanotube as functions of the WF difference, W = W M − W NT , and their comparisons with the result of the phenomenological model with V c = 0.39 eV in Eq.…”

“…We focus on metal contact and consider the situation where a metallic CNT or graphene is deposited (or epitaxially grown) on metal surfaces. Electronic and morphological properties of these interfaces have been issues of interest and a number of theoretical and experimental investigations have been made for both CNTs [8][9][10][11][12][13][14][15][16][17][18][19][20][21] and graphene 5,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] on metal surfaces. Earlier investigations for graphene on metals are reviewed in Refs.…”

Chemistry of Single-Walled Carbon Nanotubes

“…[22][23][24][25] It is now known that SWNTs can behave as metals, semiconductors, or small band-gap semiconductors, [26][27][28] depending upon their diameter and chirality. 29 Electronic transitions between the energy bands of SWNTs ( Figure 2) can be observed by standard spectroscopic techniques.…”

Detailed analysis of the mean diameter and diameter distribution of single-wall carbon nanotubes from their optical response

“…However, in consideration of the simplifying assumptions made in the analytical approach taken here we cannot obtain information about the exact distribution of nanotubes across the chiralties from bulk measurement. Further analysis methods focused on individual SWCNT's such as STS-STM, 37,38 resonant Raman, 30 and small area TEM diffraction 16,17 are required. In the context of these data and the fit results it is interesting to compare the apparent preferential formation of SWCNT with chiral angles between 15°-30°with conclusions reached from other chirality sensitive measurements of the individual SWCNT's ͑Refs.…”