Applications of carbon nanotube technology for next-generation high speed and microwave circuits

Abstract

Carbon nanotubes (CNTs) have demonstrated promising electrical, thermal, and mechanical properties. For example, CNTs have long mean free paths in the order of several micrometers (as compared to 40 nm for Cu at room temperature), resulting in low resistivity and possible ballistic transport, and an isolated CNT can carry current densities in excess of 1010 A/cm2 even at an elevated temperature of 250°C. These unique properties make them exciting prospects for a variety of applications in microelectronics/nanoelectronics, spintronics, optics, as well as material science, mechanical and biological fields, and even fundamental areas like relativistic quantum mechanics and condensed matter physics. This paper reviews the current state of research (including some research achievements of the author's group) in applications of carbon nanotube technology for high speed and microwave circuits. At first both electrical and thermal modeling and broadband characterization for various CNTs (single walled CNTs, multi walled CNTs and CNT bundles) are presented and compared each other and with conventional conductor materials to give guidelines for their prospective applications. Then various applications, including for high speed interconnects and vias, microwave passives such as inductors, capacitors, resonators, antennas, and some other fields, are introduced and discussed. The results from simulation or experiment show that some performance, such as the delay of interconnect and quality factor of microwave inductor, of interconnects or microwave passives based on CNTs is much better than that based on traditional conductors, indicating that the emerging nano-scale materials have great potential in applications for next-generation high speed and microwave circuits.