About the charge injection limitation in Schottky barrier CNTFETs

The injection of charges into the channel of a carbon nanotube (CNT) field effect transistor (FET), and, hence, the overall device behavior are strongly affected by the interface between the CNT and the metall contacts and the tube portion underneath the metall contacts (contact region). The properties of the interface and the contact region depend on details of the fabrication process and the materials used. Thus, a detailed understanding of the related phenomena facilitates device and process optimization. A major issue in optimizing the interface and the contact region is the limitation of charge injection due to potential barriers in the contact region and clipping. The limitation along with the transport within the channel is studied by means of the Boltzmann-transport equation (BTE) in combination with a phenomenological contact model which also considers tunneling through near-contact potential barriers. The related results are discussed with respect to CNT-based 1D-electronics for high-frequency (HF) analog applications.