Electrical Transport and Channel Length Modulation in Semiconducting Carbon Nanotube Field Effect Transistors

We perform finite-element analysis modeling and characterization of quasi-ballistic electrical transport in semiconducting carbon nanotube field effect transistors, and fit experimental electrical transport data from both suspended and on-substrate single-walled carbon nanotube transistors fabricated using chemical vapor deposition. Previous studies have focused on modeling ballistic transport in carbon nanotube field effect transistors, but have ignored the spatial dependence of the resistance, voltage, and Fermi energy. These spatial variations play an important role in several high voltage effects that are particularly important in the quasi-ballistic transport regime where most current or near-term devices operate. We show the relationship between device geometry and pinch-off, current saturation, and channel length modulation in the quantum capacitance regime. Output resistance is found to increase with gate coupling efficiency with a power law behavior. This model can be used for the extraction of device properties from experimental data and as a design environment tool.