Modulating the Electronic Properties along Carbon Nanotubes via Tube−Substrate Interaction

Abstract

We study single wall carbon nanotubes (SWNTs) deposited on quartz. Their Raman spectrum depends on the tube-substrate morphology, and in some cases, it shows that the same SWNT-on-quartz system exhibits a mixture of semiconductor and metal behavior, depending on the orientation between the tube and the substrate. We also address the problem using electric force microscopy and ab initio calculations, both showing that the electronic properties along a single SWNT are being modulated via tube-substrate interaction.

Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

“…3f) 13 . Possible contributions for these environment-induced Raman and absorption spectral modifications have been mainly ascribed to dielectric, chemical and mechanical effects [41][42][43][44][45] .…”

Study of Carbon Nanotube-Substrate Interaction

“…The first-principles calculations shown in Figure 3 stand for SWNT serpentine placed on top of a crystalline quartz [30]. Upon relaxation, the silicon atoms in the contact region are found to experience an upward displacement and the bottom part of the nanotube becomes flat, resulting from a strong interaction between carbon bonding states and surface dangling bonds [30]. While Figure 3 Figure 3(b)), showing the semiconductormetal transition [30].…”

“…The formation of these structures can be explained by the mechanism called "falling spaghetti" [23,46]. This structure provides a great deal of information because the same SWNT exhibits different interactions due to the tubesubstrate morphology [30]. The first-principles calculations shown in Figure 3 stand for SWNT serpentine placed on top of a crystalline quartz [30].…”

“…This structure provides a great deal of information because the same SWNT exhibits different interactions due to the tubesubstrate morphology [30]. The first-principles calculations shown in Figure 3 stand for SWNT serpentine placed on top of a crystalline quartz [30]. Upon relaxation, the silicon atoms in the contact region are found to experience an upward displacement and the bottom part of the nanotube becomes flat, resulting from a strong interaction between carbon bonding states and surface dangling bonds [30].…”

“…In fact, recent studies have shown that a strong interaction between carbon nanotubes and the substrate can lead to important changes in the nanotube properties. For example, single-wall carbon nanotubes (SWNTs) deposited on quartz gives rise to a superlattice of semiconductor and metal system, where the conduction behavior depends on the orientation between the tube and the substrate [30]. That is, the tube and the substrate are actually a new system that cannot be considered as only the sum of tube plus substrate.…”