Transport study of gate and channel engineering on the surrounding-gate CNTFETs based on NEGF quantum theory

In this paper, we comprehensively study the effects of gate and channel engineering on the performances of surrounding-gate CNTFETs using a quantum kinetic model, which is based on two-dimensional non-equilibrium Green functions (NEGF) solved self-consistently with Poisson’s equations. The iterative approach between Poisson equation and NEGF has been discussed. For the first time, the influences of double-material-gate and linear doping structures on the CNTFETs have been investigated. The calculated results show that double-material-gate CNTFETs with conventional doping (DMG-CNTFETs) can effectively suppress the drain-induced barrier lowering (DIBL), short-channel effects (SCEs), and achieve better sub-threshold property as compared with single-material-gate CNTFETs with conventional doping (SMG-CNTFETs). Compared with conventional doping, linear doping presents lower leakage current, higher I _on /I _off ratio, and lower sub-threshold swing, which means a better ability of gate controlling. In addition, we present a detailed discussion of the performances of scaling down, and conclude that DMG structure can meet the ITRS’10 requirements better than SMG, especially that the I _on /I _off ratio is two orders of magnitude higher than that of ITRS’10 requirements.