As the scaling limits for Si transistors are reached, new materials are being investigated as building blocks for future nanoelectronics. Carbon nanotubes with molecular scale diameters (roughly 50,000 times less than the thickness of a human hair) are one of such novel materials that are being actively explored. In this paper, by incorporating high-k dielectric films with nanotube transistors, we have set a new limit for the switching performance of 1D nanoscale devices. The conclusion of the work is quite important as it introduces carbon nanotubes as ideal candidates for replacing the conventional Si technology.

  Does it describe a new discovery or new methodology that's useful to others? 

This is the first time that high-k dielectric films have been used for top gating of carbon nanotube transistors with high performances. In contrast to the conventional Si devices, we find that high-k integration does not cause any degradation in the carrier mobility of our devices. This is attributed to the chemical robustness and lack of surface dangling bonds in nanotubes. As a result, we have been able to obtain transistors with both low power consumption and high performance switching operations. These 1D nanotube transistors are superior in performance over the state-of-the-art Si devices.

  How did you become involved in this research?

Interested to explore the potentials of carbon nanotubes as electronic building blocks, we decided to improve the electrostatic gating of our devices by incorporating high-k gate dielectrics. To our surprise, the nanotubes survived the high-k deposition process, and we were able to achieve the highest performance transistors to date.

  Could you summarize the significance of your paper in layman's terms?

We have been able to demonstrate very high performance electronic switches made of 1D carbon nanotubes. These carbon-based transistors outperform the state of the art Si switches, which are commonly used in most digital applications, including computers.

Hongjie Dai
Associate Professor
Department of Chemistry, Stanford University 
Stanford, CA, USA