Conference Paper

Semi-analytical model for schottky-barrier carbon nanotube and graphene nanoribbon transistors.

DOI: 10.1145/1785481.1785538 Conference: Proceedings of the 20th ACM Great Lakes Symposium on VLSI 2009, Providence, Rhode Island, USA, May 16-18 2010
Source: DBLP

ABSTRACT This paper describes a physics-based semi-analytical model for Schottky-barrier carbon nanotube (CNT) and graphene nanoribbon (GNR) transistors. The model includes the treatment of (i) both tunneling and thermionic currents, (ii) ambipolar conduction, i.e., both electron and hole current components, (iii) ballistic transport, and (iv) multi-band propagation. Further, it reduces the computational complexity in the two critical and time-consuming steps, namely the calculation of the tunneling probability and the self-consistent evaluation of the the surface potential in the channel. When validated against NanoTCAD ViDES, a quantum transport simulation framework based on the non-equilibrium Green's function method, it is several orders of magnitude faster without significant loss in accuracy. Since the model is physics-based, it is parameterizable and can be used to study the effect of common parametric variations in CNT diameter and GNR width, Schottky-barrier height, and insulator thickness.

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    ABSTRACT: Contact effects of carbon nanotubes to metallic electrodes have a big impact on the electronic transport in CNT-based structures. In general there are two expected types of contacts, Schottky type with semiconducting tubes and ohmic contact with semiconducting and metallic tubes. However not always perfect contacts come, it is rather a tunneling barrier contact because of the weak coupling to the metal electrode or the formation of thin layer of oxides at the interface, for examples. We propose a simple model for non-ideal contacts of metallic single walled nanotube in order to calculate the overall resistance and hence the contact resistance. The model takes into account the findings of both experiments and theories such as effect of work function, electron phonon scattering in low and high bias voltage, image potential and van derWaals distance at the interface. The model can be developed to calculate the contact resistance for strips of several SWNTs or multi walled carbon nanotubes.
    Transaction on Systems, Signals and Devices. 11/2013; Vol. 8(4):427-439.

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