High-frequency performance of multiple-channel carbon nanotube transistors

We have measured the high-frequency characteristics of carbon nanotube field effect transistors (CNTFETs) and obtained a cut-off frequency of 10.3 GHz and maximum oscillation frequency of 3.5 GHz. These values are among the highest ever published. We achieved them by developing a highdensity multiple-channel CNTFET structure whose output impedance is much lower than conventional single channel CNTFETs, and by accurately measuring S-parameters, e.g., using the de-embedding procedure that removes existing errors in measured S-parameters of small-signal devices. We also described an equivalent circuit RF model consistent with the experimental results. Detailed analysis revealed that decreasing parasitic capacitances of electrodes and resistances of carbon nanotube extensions greatly improve the high-frequency performance of CNTFETs. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.