DFT Modeling of Bulk-Modulated Carbon Nanotube Field-Effect Transistors

We report density-functional theory (DFT) atomistic simulations of the nonequilibrium transport properties of carbon nanotube (CNT) field-effect transistors (FETs). Results have been obtained within a self-consistent approach based on the nonequilibrium Green's functions (NEGF) scheme. We show that, as the current modulation mechanism is based on the local screening properties of the nanotube channel, a completely new, negative quantum capacitance regime can be entered by the device. We show how a well-tempered device design can be accomplished in this regime by choosing suitable doping profiles and gate contact parameters. At the same time, we detail the fundamental physical mechanisms underlying the bulk-switching operation, including them in a very practical and accurate model, whose parameters can be easily controlled in order to improve the device performance. The dependence of the nanotube screening properties on the temperature is finally explained by means of a self-consistent temperature analysis

[1]  K. Natori.  Ballistic metal-oxide-semiconductor field effect transistor , 1994 .

[2]  S. Luryi.  Quantum capacitance devices , 1988 .

[3]  L. Keldysh.  Diagram technique for nonequilibrium processes , 1964 .

[4]  Jerry Tersoff,et al.  Novel Length Scales in Nanotube Devices , 1999 .

[5]  Thomas Frauenheim,et al.  Atomistic simulations of complex materials: ground-state and excited-state properties , 2002 .

[6]  A. Carlo,et al.  Atomistic theory of transport in organic and inorganic nanostructures , 2004 .

[7]  S. Tans,et al.  Room-temperature transistor based on a single carbon nanotube , 1998, Nature.

[8]  Gold,et al.  Attraction induced by many-body effects in the quasi-one-dimensional electron gas. , 1995, Physical review. B, Condensed matter.

[9]  Markus Buttiker,et al.  Capacitance, admittance, and rectification properties of small conductors , 1993 .

[10]  P. McEuen,et al.  Single-walled carbon nanotube electronics , 2002 .

[11]  S. Wind,et al.  Field-modulated carrier transport in carbon nanotube transistors. , 2002, Physical review letters.

[12]  P. Ordejón,et al.  Density-functional method for nonequilibrium electron transport , 2001, cond-mat/0110650.

[13]  J. Knoch,et al.  High-performance carbon nanotube field-effect transistor with tunable polarities , 2005, IEEE Transactions on Nanotechnology.

[14]  Paolo Lugli,et al.  Theoretical tools for transport in molecular nanostructures , 2002 .

[15]  Phaedon Avouris,et al.  Ambipolar-to-Unipolar Conversion of Carbon Nanotube Transistors by Gate Structure Engineering , 2004 .

[16]  West,et al.  Negative compressibility of interacting two-dimensional electron and quasiparticle gases. , 1992, Physical review letters.

[17]  A. Carlo,et al.  Negative quantum capacitance of gated carbon nanotubes , 2005 .

[18]  A. Fetter,et al.  Quantum Theory of Many-Particle Systems , 1971 .

[19]  Mark S. Lundstrom,et al.  A numerical study of scaling issues for Schottky-barrier carbon nanotube transistors , 2003, IEEE Transactions on Electron Devices.

[20]  Sándor Suhai,et al.  Self-consistent-charge density-functional tight-binding method for simulations of complex materials properties , 1998 .

[21]  S.Heinze,et al.  Carbon Nanotubes as Schottky Barrier Transistors , 2002, cond-mat/0207397.

[22]  M. Radosavljevic,et al.  Tunneling versus thermionic emission in one-dimensional semiconductors. , 2004, Physical review letters.

[23]  Giorgos Fagas,et al.  Introducing Molecular Electronics: A brief overview , 2006 .

[24]  J. Appenzeller,et al.  Band-to-band tunneling in carbon nanotube field-effect transistors. , 2004, Physical review letters.

[25]  P. Avouris,et al.  Self-aligned carbon nanotube transistors with charge transfer doping , 2005, cond-mat/0511039.

[26]  A. Carlo,et al.  One-dimensional screening effects in bulk-modulated carbon nanotube transistors , 2006 .

[27]  West,et al.  Compressibility of the two-dimensional electron gas: Measurements of the zero-field exchange energy and fractional quantum Hall gap. , 1994, Physical review. B, Condensed matter.

[28]  M. Radosavljevic,et al.  Drain voltage scaling in carbon nanotube transistors , 2003, cond-mat/0305570.

[29]  J. C. Slater,et al.  Simplified LCAO Method for the Periodic Potential Problem , 1954 .

[30]  Pawel Danielewicz,et al.  Quantum theory of nonequilibrium processes, I , 1984 .