Intrinsic current gain cutoff frequency of 30GHz with carbon nanotube transistors

Abstract

High frequency capabilities of carbon nanotube field-effect transistors (CNTFETs) are investigated. Structures with a large number of single-walled carbon nanotubes were fabricated using dielecrophoresis to increase the density of nanotubes in the device channel. The authors obtained an intrinsic current gain cutoff frequency of 30GHz establishing state-of-the-art high frequency (hf) potentialities of CNTFETs. The device also showed a maximum stable gain above 10dB at 20GHz. Finally, the parameters of an equivalent circuit model of multitube CNTFET at 20GHz are determined, which open the route to the modeling of nanotubes-based hf electronics.

Order-Nelectron transport calculations from ballistic to diffusive regimes by a time-dependent wave-packet diffusion method: Application to transport properties of carbon nanotubes

“…High cut-off frequency is essential to realize the high-speed response of devices. Recent experimental works have demonstrated the cut-off frequencies up to 50 GHz using the CNT-FETs with a few hundred nanometers channel length, [60][61][62][63][64] and the phenomenological law has been also obtained. 65 Although the cut-off frequency of CNT-FET with a 2 nm gate is estimated to reach as high as 1.6 THz using the nonequilibrium Green's-function method, 66 the length dependence of the cut-off frequency from the ballistic to diffusive regimes has not been clarified yet theoretically.…”

Regional Signal-Delay Analysis Applied to High-Frequency Carbon Nanotube FETs

“…Applying charge-control theory [10] to FETs, the overall, source-drain signal delay time relates to , and to the change in input charge that is required to bring about a change in output current (1) where, for a FET, is the change in charge on the gate, and is the change in drain current. Here, we consider the changes in charge and current due to a change in gate-source voltage .…”

“…T HE SMALL size, unusual topography, and technological immaturity of carbon nanotube field-effect transistors (CNFETs) have contributed, no doubt, to the fact that the present record for their measured unity-current-gain frequency is a modest 30 GHz [1]. For the moment, then, we need to rely on simulations to get a better idea of the high-frequency capability of CNFETs.…”

Terahertz science and technology of carbon nanomaterials

“…Experimentally, several field-effect transistors based upon individual nanotubes, operating in the low GHz range have been achieved [155][156][157][158][159][160][161][162][163]. However intrinsic cutoff frequencies in the THz regime have yet to be realized.…”

“…The performance of such devices have been limited by parasitic effects and impedance mismatches. One approach to increase the extrinsic cutoff frequency is to utilize networks or arrays of aligned nanotubes [158,[164][165][166][167][168][169][170][171][172][173]. Most recently, Che et al [174] demonstrated that such an array of carbon nanotube transistors can achieve an extrinsic current-gain cutoff frequency of 25 GHz.…”