1 Design and Simulation of MOSCNT with Band Engineered Source and Drain Regions Narjes Moghadam, Mohammad Kazem Moravvej-Farshi*, and Mohammad Reza Aziziyan Faculty of Electrical and Computer Engineering, Advanced Devices Simulation Laboratory (ADSL), Tarbiat Modares University (TMU), P. O. Box 14115-194, Tehran 1411713116, Iran. *Corresponding author: farshi_k@modares.ac.ir Abstract We propose a new Metal-oxide-semiconductor carbon-nanotube transistor (MOSCNT) in which source (S) and drain (D) regions are formed by band engineered multi-wall carbon nanotubes (BE-MWCNTs). The gradual potential profiles of these band-engineered S/D regions weakening the longitudinal confinements in the channel reduce the band-to-band tunneling significantly and hence eliminating the ambipolar behavior observed in other types of MOSCNTs. Such an excellent performance makes the proposed band engineered MWCNT a potential alternative to the chemically/electrostatically doped CNTs that are usually used as S/D regions in MOSCNTs. Simulations show that the proposed band engineered MOSCNT (BE- MOSCNT) outperforms the lightly-doped drain and source (LDDS) MOSCNT, in both ON and OFF regimes. The LDDS- MOSCNT has already proven to outperform the conventional MOSCNTs. The proposed BE-MOSCNT, in comparison with its earlier rivals, exhibits smaller subthreshold swing, smaller drain-induced barrier lowering, and lower OFF currents. Thus, in this respect, it could be more attractive to circuit designers. To simulate the device band structure and I-V characteristics, we have employed the non-equilibrium Green function (NEGF) formalism using the modified Hamiltonian and tight-binding approximation with only p z -orbitals. Keywords: Metal-oxide-semiconductor carbon-nanotube transistors (MOSCNT); Band engineered multi-wall carbon nanotubes (BE-MWCNTs); Ambipolarity; Band to band tunneling; non-equilibrium Green function (NEGF) 1. Introduction In recent years, by size miniaturization and progress in nanotechnology, carbon nanotube field-effect transistors (CNTFETs) have received great attentions, in electronic and optoelectronic applications [1,2,3]. Due to the formation of potential barriers at the interface of CNTs and metal contacts, most CNTFETs operate as Schottky barrier transistors (SB-CNTFETs). However, large sub-threshold swings, ambipolar behavior, and low ON/OFF current ratios are characteristics that can limit the use of SB- CNTFETS, in logic circuits [4]. MOSFET-like CNTFETs known as Metal-oxide-semiconductor carbon-nanotube transistors (MOSCNTs) fabricated by doped CNTs as source (S) and drain (D) regions are shown to have higher current ratios and smaller sub-threshold swings [5]. Nevertheless, I-V characteristics of MOSCNTs under high reverse gate voltages exhibit large leakage