Contact Conductivity of Uncapped Carbon Nanotubes Formed by Silicon Carbide Decomposition

Abstract

Understanding of the contact conductivity of carbon nanotubes (CNTs) will contribute to the further application of CNTs for electronic devices, such as thin film transistors whose channel or electrode is made of dispersed CNTs. In this study, we estimated the contact conductivity of a CNT/CNT interface from the in-plane conductivity of an uncapped CNT forest on SiC. Investigation of the electrical properties of dense CNT forests is also important to enable their electrical application. The in-plane conductivity of a dense CNT forest on silicon carbide normalized by its thickness was measured to be 50 S/cm, which is two to three orders of magnitude lower than the conductivity of a CNT yarn. It was also found that both the CNT cap region and the CNT bulk region exhibit in-plane conductivity. The contact conductivity of CNTs was estimated from the in-plane conductivity in the bulk region. Dense and uncapped CNT forest can be approximated by a conductive mesh, in which each conductive branch corresponds to the CNT/CNT contact conductance. The evaluated contact conductivity was in good agreement with that calculated from the tunneling effect.

Vertical edge graphite layer on recovered diamond (001) after high‐dose ion implantation and high‐temperature annealing

“…If the graphene sheets in the VEG are aligned in the direction of diamond [110], the VEG images of these rotated samples should look amorphous. Therefore, this VEG structure is not aligned with the direction of diamond [110] or but is instead randomly rotated around the diamond [001]‐axis. Figure a shows the TEM image of sample B, which is fabricated using the same conditions as those for sample A except that it is fabricated on a high‐pressure high‐temperature (HPHT)‐grown diamond substrate.…”

“…Highly‐oriented nanocarbon materials such as graphene and carbon nanotubes (CNTs) have unique potential characteristics for electrical , thermal , and mechanical applications. Further, diamond is a promising wide‐bandgap semiconductor material for high‐current conducting materials in power semiconductors.…”

“…In general, a carbon cap layer formed by depositing carbonized resist or by a sputter process is used in the HTA process to avoid surface graphitization. Nevertheless, CNT forests formed on SiC have been reported to be suitable as electrodes for SiC power device applications . Further, a dense CNT forest has been found to be a good ohmic contact material for n‐type SiC, in conjunction with its high on‐axis conductivity and high thermal conductivity .…”

Ohmic Contact for Silicon Carbide by Carbon Nanotubes

“…A CNT forest formed by SiC surface decomposition [1][2][3][4] is a densely packed forest and is ideal for application as not only a heat sink [1] but also an ohmic contact in SiC power transistors. [2] We have reported the contact resistivity of CNT/SiC interfaces comprising a CNT forest on SiC covered with a metal (Au/Ti). [2] In addition, CNTs on SiC have considerable conductivity in in-plane directions.…”

“…[2] We have reported the contact resistivity of CNT/SiC interfaces comprising a CNT forest on SiC covered with a metal (Au/Ti). [2] In addition, CNTs on SiC have considerable conductivity in in-plane directions. [3] In this study, we measured the contact resistivity and Schottky barrier height of a CNT/SiC interface without a covering material and compared it with the results of previous work.…”