Design and simulation of MOSCNT with band engineered source and drain regions

• Published in: Microelectronics and reliability Vol. 53; no. 4; pp. 533 - 539
• Main Authors: Moghadam, Narjes, Moravvej-Farshi, Mohammad Kazem, Aziziyan, Mohammad Reza
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-04-2013; Elsevier
• Subjects: Applied sciences; Beryllium; Channels; Circuit design; Cross-disciplinary physics: materials science; rheology; D region; Devices; Drains; Electronics; Exact sciences and technology; Materials science; Molecular electronics, nanoelectronics; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Simulation; Swing; Transistors; Performance evaluation; Band structure; Semiconductor materials; Voltage current curve; Nanotube devices; Lightly doped drain; Tunnel effect; Doped materials; Carbon nanotubes; Transistor; Green function; Nanoelectronics; Multiwalled nanotube; Tight binding approximation; Non equilibrium conditions; Ambipolar diffusion; Hamiltonian; Comparative study; DIBL effect; On off effect
• ISSN: 0026-2714; 1872-941X
• DOI: 10.1016/j.microrel.2012.11.007

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 pz-orbitals.