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The effects of linear doping profile near the source and drain contacts on the switching and highfrequency characteristics for conventional single-material-gate CNTFET(C-CNTFET) and hetero-material-gate CNTFET(HMG-CNTFET) have been theoretically investigated by using a quantum kinetic model.This model is based on two-dimensional non-equilibrium Green’s functions(NEGF) solved self-consistently with Poisson’s equations.The simulation results show that at a CNT channel length of 20 nm with chirality(7,0),the intrinsic cutoff frequency of C-CNTFETs reaches up to a few THz.In addition,a comparison study has been performed between C-and HMG-CNTFETs.For the C-CNTFET,results reveal that a longer linear doping length can improve the cutoff frequency and switching speed.However,it has the reverse effect on on/off current ratios.To improve the on/off current ratios performance of CNTFETs and overcome short-channel effects(SCEs) in high-performance device applications,a novel CNTFET structure with a combination of an HMG and linear doping profile has been proposed.It is demonstrated that the HMG structure design with an optimized linear doping length has improved high-frequency and switching performances as compared to C-CNTFETs.The simulation study may be useful for understanding and optimizing high-performance of CNTFETs and assessing the reliability of CNTFETs for prospective applications.
The effects of linear doping profile near the source and drain contacts on the switching and high frequency features for conventional single-material-gate CNTFETs (C-CNTFETs) and hetero-material-gate CNTFETs (HMG-CNTFETs) have been theoretically investigated by using a quantum kinetic model. This model is based on two-dimensional non-equilibrium Green’s functions (NEGF) solved self-consistently with Poisson’s equations. The simulation results show that at a CNT channel length of 20 nm with chirality (7,0), the intrinsic cutoff frequency of C-CNTFETs up to a few THz. addition, a comparison study has been performed between C-and HMG-CNTFETs.For the C-CNTFET, results reveal that a longer linear doping length can improve the cutoff frequency and switching speed. However, it has the reverse effect on on / off current ratios. To improve the on / off current ratios performance of CNTFETs and overcome short-channel effects (SCEs) in high-performance device applications, a novel CNTFET structure with a combination of an HMG and linear doping profile has been proposed. It is demonstrated that the HMG structure design with an optimized linear doping length has improved high-frequency and switching performances compared to C-CNTFETs. The simulation study may be useful for understanding and optimizing high-performance of CNTFETs and assessing the reliability of CNTFETs for prospective applications.