Self-aligned ballistic molecular transistors and electrically parallel nanotube arrays

Carbon nanotube field-effect transistors with structures and properties near the scaling limit with short (down to 50 nm) channels, self-aligned geometries, palladium electrodes with low contact resistance, and high-kappa dielectric gate insulators are realized. Electrical transport in these miniature transistors is nearly ballistic up to high biases at both room and low temperatures. Atomic-layer-deposited (ALD) high-kappa films interact with nanotube sidewalls via van der Waals interactions without causing weak localization at 4 K. New fundamental understanding of ballistic transport, optical phonon scattering, and potential interfacial scattering mechanisms in nanotubes is obtained. Also, parallel arrays of such molecular transistors are enabled to deliver macroscopic currents-an important milestone for future circuit applications.