Novel Attributes in the characteristics and short channel effects of double gate carbon nanotube field-effect transistors

In this paper, the short channel effects of different gate configurations and geometry parameters of carbon nanotube (CNT) field-effect transistors with doped source and drain extensions are investigated. The simulation is based on the self-consistent solution of the three-dimensional Poisson equation and Schrödinger equation with open boundary conditions,within the nonequilibrium Green’s function formalism. Simulation results show that double gate structure offers quasi-ideal subthreshold slope and drain induced barrier lowering even for the rather thick oxide (5nm). Then, the investigation of electrical characteristics of double gate carbon nanotube field-effect transistor (DG-CNTFET) shows that as the CNT normalized density or CNT diameter increases, the current in the on-state increases as well. Also, the off-state current in DG-CNTFET decreases with increasing drain voltage. Furthermore, in the negative gate voltages, for a large drain voltage, increasing in drain current due to band to band tunneling requires a larger negative gate voltage, and for low drain voltage, resonant states appear.