Characterization of Quasi-Metallic Tunnel-Field-Effect-Transistors

Band-to-band tunneling mechanism has proven to be a promising alternative to thermionic diffusion for ultra-fast switching applications. Tunneling Field-Effect-Transistors (TFETs), which primarily operate based on tunneling current, can offer low turn-on voltage with low sub-threshold swing[1]. Here, we demonstrate TFETs based on suspended, ultra-clean, quasi-metallic carbon nanotube pn devices. These devices exhibit a subthreshold swing as low as 2mV/decade, with a current Ion/Ioff ratio in the order of 105 at cryogenic temperatures. At room temperature, however, the current is dominated by the diffusion of carriers, which degrades the Ion/Ioff ratio and the subthreshold swing. We also explore the effect of the schottky contacts on the tunneling current by adding two back-to-back diodes to the tunneling current model. Our results provide evidence that the effect of the schottky contacts can be significant when quasi-metallic nanotubes exhibit band-to-band tunneling. Our results show that quasi-metallic carbon nanotubes can be potential candidates for future nanoelectronics. References: [1] A. M. Ionescu and H. Riel, "Tunnel field-effect transistors as energy-efficient electronic switches," Nature, vol. 479, pp. 329-337, 2011.