Shi Zu-Jin

Vertical assembly of carbon nanotubes for via interconnects

The via interconnects are key components in ultra-large scale integrated circuits (ULSI). This paper deals with a new method to create single-walled carbon nanotubes (SWNTs) via interconnects using alternating dielectrophoresis (DEP). Carbon nanotubes are vertically assembled in the microscale via-holes successfully at room temperature under ambient condition. The electrical evaluation of the SWNT vias reveals that our DEP assembly technique is highly reliable and the success rate of assembly can be as high as 90%. We also propose and test possible approaches to reducing the contact resistance between CNT vias and metal electrodes.

Single wall carbon nanotubes and their electrical properties

Single-wall carbon nanotubes (SWCNTs) were synthesized and purified. A water colloid of SWCNTs was prepared and used to assemble SWCNTs onto a gold film surface. Scanning tunneling microscopy (STM) images showed that short SWCNTs stood on gold film surfaces. Using STM tips made of SWCNTs, a crystal grain image of a gold thin film and an atomic resolution image of highly oriented pyrolytic graphite were successfully obtained. The electrical properties of short SWCNTs, which stood on the surface of gold film, were measured using STM. That SWCNTs stand on gold thin films is a promising technique for studying structures and properties of carbon nanotubes, as well as assembling and fabricating high-intensity coherent electron sources, field emission flat panel display, tips for scanning probe microscopes, new nanoelectronic devices, etc.

Influence of nitrogen precursors on the structure, composition, and oxygen reduction reaction performance of dual heteroatom doped carbon nanohorns

Heteroatom doped single-walled carbon nanohorns are produced via a facile one-step arc discharge method and used as metal-free catalysts for the oxygen reduction reaction (ORR). The influence of nitrogen-source on the structure and electrocatalytic activity of the nanohorns is studied. Two kinds of N doped carbon nanohorns produced by N2 or melamine as the N-source, respectively, present similar structure. However, dual-doped carbon nanohorns fabricated from different N-sources possess different structures. NB-dual doped carbon nanohorns synthesized by N2 would contain the enormous h-BN, which is chemical-inert for ORR. But using melamine as the N-source would prevent this phenomenon and raise the doping of B atoms into the graphene lattice, which lead to the increased ORR catalytic activity. Different with NB-dual doping, NP-dual doping via N2 would greatly give a rise to the content of N atoms into the materials, and result in the enhanced limited current intensity.

Preparation and Catalytic Properties of SWNTs-Supported Pd Catalyst

A Pd catalyst supported by single-walled carbon nanotubes (SWNTs) was prepared by a redox reaction between SWNTs and PdCl2 solution. The supported catalyst was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermo-gravimetric (TG) techniques. Results showed that large quantities of Pd particles with diameters of ca 2 nm distributed evenly on the surface of SWNTs and the content of Pd was 14.13% (w, mass fraction) when using SWNTs and 12 mmol·L-1 PdCl2 as reactants. The supported catalyst, after reduction by H2, exhibited high catalytic activity in Suzuki reaction. The yield of biphenyl was 98.10% after 30 min reaction at 90 ℃.