Theoretical investigation of carbon nanotube devices for millimeter/submillimeter wave analog circuits

Abstract

Carbon nanotubes have become a very exciting area of research in the field of nanoelectronics in the past few years. Diodes and transistors fabricated using carbon nanotubes are theoretically very promising. Although, experimentally these devices are challenging to successfully realize it is hoped that further research and improvements in fabrication procedures will yield devices which could match or surpass current CMOS technologies. However, there are still many areas that need to be improved before anyone sees these devices mass produced commercially. This thesis gives a detailed overview of the fundamentals of these devices which can be easily understood by someone with a typical electrical engineering background. The purpose of this thesis is to investigate both the theory behind these devices and to conduct a series of simulations in order to determine how they compare to ultimately scaled CMOS for high frequency applications by ignoring the challenges associated with fabricating these devices reliably. In other words, at best how could these devices perform if they could be mass produced with high yield compared to current technologies? First an introduction to carbon nanotubes and a review of relevant concepts from solid-state electronics will be given, followed by a brief overview of quantum theory for 1-D systems as it pertains to nanotube based electronics. This will then be used to develop models for a Schottky diode and Schottky barrier transistor. Simulations using these models were conducted that show the potential for these devices for high frequency electronics. These results are subsequently used to compare to current state-of-the-art technologies. Upon completion of the simulations in this thesis, it was determined that carbon nanotube based Schottky diodes and Schottky barrier transistors do not perform as well as current technologies in relation to applications for submillimeter/millimeter wave detection and analog circuits, even when assuming no limitations imposed due to poor fabrication.