Low-Resistant Carbon Nanotube – Carbide – Metal

Optimization of the contacts between a carbon nanotube (CNT) and a metal electrode is of central importance for improving the performance of various CNT-based devices. A perfect contact should behave properly with respect to both mechanical robustness and reliability and electrical conductance. So far, most efforts have been devoted to pursuing the optimal contact materials and effective processing methods that enable low-resistant ohmic CNT-metal nanocontacts. [ 1–6 ] However, in many applications, the contacts with excellent electronic properties alone can not ensure stable operation of the whole system, especially when they are not mechanically strong. For instance, during the applications of CNTs as electron fi eld-emitters, one of the key problems that may severely reduce the emission stability and lifetime of a device is the abrupt dispatch of CNTs from the metal substrate under external electric fi eld. Such emission failure has been attributed to the relatively weak bonding between CNTs and metal supports. [ 7,8 ] Additionally, CNTs are well-known as the strongest material found on Earth to date, however, the superiority of their strength would not be realistically employed without having solid contacts over their entire periphery within a given nanoelectromechanical system. In particular, direct contact between all the CNT shells and metal surfaces is highly desirable, not only for multishelled electron transport and low contact resistance but also for multishelled load bearing and ultimate connection rigidity. Theoretical calculations have suggested that two types of CNT-metal contacts exist, weak physical and strong chemical ones, depending on the coupling of d-orbitals of metals and p-orbitals of carbon atoms. [ 9–13 ] The contact type can determine both the electronic interaction and cohesive strength at the contact. Although the electronic properties of the contacts between CNT and various metals have been intensively studied in the experiments, the attempt to experimentally fi nd the strongest metal-CNT connections and to quantitatively evaluate their mechanical properties still remains challenging due to many technical diffi culties. In this work, we employ the mechanical properties measurements on a new type of multiwalled CNT-tungsten carbidetungsten contacts, in which all the shells of a CNT solder directly to the surface of a tungsten wire. The extremely high tensile strength, approaching 15 GPa, was measured on such