Tuning the electrical transport properties of double-walled carbon nanotubes by semiconductor and semi-metal filling

Abstract

Manipulating the electrical properties of carbon nanotubes through semi-metal or semiconductor filling is of paramount importance in the realization of nano-electronic devices based on one dimensional composite materials. From low temperature electrical conductivity measurements of a network, of empty and filled double-walled carbon nanotubes (DWNT’s), we report a transition in electrical transport features from hopping to weakly activated conduction by HgTe filling and also semi-metallic conduction in selenium (Se) filled DWNT’s. Magneto-resistance (MR) studies of the filled DWNT’s show suppression of the hopping conduction and a signature of 3D weak localization for Se@DWNT’s at low temperatures and high magnetic fields. These results are discussed on the basis of strength of interaction between the filler material and the inner-walls of the host DWNT’s, which enhances the electronic density of states (DOS) in the material as well as the change in the property of the filler material due to constrained encapsulation.

SiOCN Functionalized Carbon Nanotube Gas Sensors for Elevated Temperature Applications

“…After 250°C, the conductance decreases irreversibly due to structural modification . The reversible increase in the conductivity (≤250°C) is explained by the semiconductor nature of the sample, whereas the decrease in the conductance can be explained by the transformation from semiconductor to metallic behavior . The reversible trend under dry air and humid air up to 250°C is verified for our CF/CNT/SiOCN sensor.…”

“…The activation energy of CF/CNT/SiOCN is calculated as low as 1 meV for the 1st step and other cooling steps (<440°C). This kind of extremely small band gap is reported in literature for semimetallic CNTs whose diameter is slightly greater than 1 nm . This is considered as an indication of the formation of thin layer of SiOCN on CNTs.…”

“…These studies show that CNTs are very sensitive to high temperatures, and decompose easily when expose to air and have a reversible response only up to 250°C. After 250°C, the conductance decreases irreversibly due to structural modification . The reversible increase in the conductivity (≤250°C) is explained by the semiconductor nature of the sample, whereas the decrease in the conductance can be explained by the transformation from semiconductor to metallic behavior .…”

Temperature-dependent diffusive to ballistic transport transition in aligned double walled carbon nanotubes in the high frequency regime

“…3 Earlier experimental and theoretical works on filled DWNTs have shown that these nanotubes demonstrate unique1D features due to the nearly structurally perfect inner wall that is protected by the outer wall. 6,7 The inner wall thus remains unaffected by the chemical purification processes, and substrate interference effects although the outer wall of DWNTs can be biased in such a manner it behaves as a gate. 8 However, the alignment of the tubes is necessary to observe 1D transport which can be affected by the interaction of tubes in a bundle of CNTs.…”

Structure of inorganic nanocrystals confined within carbon nanotubes

“…Their cylindrical shape and chemical structure (honeycomb carbon lattice) confer the material unique properties with potential applications in biomedicine [1,2], catalysis [3], nanocomposites [4] or electronics [5]. Their range of application can be further expanded by the formation of hybrid materials via endohedral filling [6][7][8][9] or external decoration [10,11]. The encapsulation at the nanoscale, which is the focus of the present review, allows tuning the properties of both the guest species that can undergo modifications of their space configuration, crystalline structure or the atomic ratio of their constituting elements [7] and the host, which electronic and optical properties can also be impacted due to the interaction between the new encapsulated material and the walls of the nanotubes [8,9].…”