The current era of CNT research began in 1991 when Sumio Iijima of Nippon Electrical Corporation's (NEC) Fundamental Research Laboratory in Tsukuba, Japan, synthesized MWCNTs using arc-discharge evaporation from a carbon anode and characterized them with transmission electron microscopy. Subsequent research by groups at NEC and International Business Machines Corporation (IBM) in 1993 produced SWCNTs by incorporating a metal catalyst into the cathode. Chronologically, CNTs were discovered between the isolation of fullerenes in 1985 and graphene in 2004. A timeline of the key events in the history of CNT research is shown in Figure . These include efforts to synthesize CNTs using new methods or into alternate form factors, understand the properties of CNTs through characterization and modeling, and evaluate and optimize their performance in various applications. Shortly after their discovery, three theoretical studies provided valuable insights on the electronic properties of SWCNTs. By calculating the electronic structures of SWCNTs, these studies predicted that individual tubes could have either metallic or semiconducting electrical properties, depending on their chirality and diameter. Furthermore, they determined that Peierls distortion, which can interfere with the electrical conductivity of 1-D metals, was not a significant effect in metal-like SWCNTs at ambient temperature. The theoretical predictions in these publications would later be confirmed by direct measurement of diameter and chirality using scanning tunneling microscopy, combined with measurement of the electrical properties of individual CNTs. Building on this work, in 1998 research groups at Delft University of Technology and IBM fabricated CNT-based field-effect transistors (FETs), placing individual SWNTs over a siliconbased gate structure between metallic electrodes, similar to a doped Si-based FET. Over the next 15 years, 20 full logic circuits and eventually a computer were built using CNTs as the active components.