TB_Sim is a k.p and tight-binding code developed at CEA Grenoble. It is able to compute the structural, electronic, optical and transport properties of various kinds of nanostructures such as semiconductor nanocrystals, nanowires and carbon nanotubes.
The principle of the tight-binding method is to expand the wave functions of the electrons in a basis of atomic orbitals. Indeed, the physics of silicon for example is dominated (around the band gap) by the hybridization of the 3s, 3p (and 3d) orbitals of the Si atoms (see Fig. 1). Since atomic orbitals are localized in real space, their interactions are limited to a few nearest neighbors. Computing these interactions with a self-consistent ab initio method such as density functional theory is, however, very expensive for a few thousand atoms. The interactions between atomic orbitals are, nonetheless, usually close to bulk interactions in such systems. In the semi-empirical tight-binding framework, they are therefore adjusted to reproduce the bulk band structures, then transferred to the nanostructures. This approach is very efficient and accurate enough when the bonding does not differ too much from the bulk reference.
|Fig. 1: (top) From silicon atoms to bulk silicon: links between then atomic orbitals and the bulk band structure. (bottom) The s, p, and d orbitals.|
Since the interactions between atomic orbitals are limited to first, second or third nearest neighbors, the tight-binding hamiltonian is "sparse" (most matrix elements are zero): This makes the tight-binding method very appropriate for the design of "order N" methods whose computational cost scales linearly with the number N of atoms. For example, the cost of a matrix/vector product scales as N for a sparse tight-binding hamiltonian instead of N2 for a dense matrix. The optical properties of a million atom system can therefore be computed within a few hours on a desktop computer.
|Fig. 2: Multiscale modelling - Ab initio calculations on few atom systems are used to provide inputs to semi-empirical atomistic methods such as tight-binding, then to large-scale calculations based, e.g., on finite-element modelling. These methods can also be coupled together to describe different parts of the system with very different length or time scales.|
As an atomistic approach, the tight-binding method is well suited to the description of atomic-scale features such as impurities, defects, electron-phonon coupling, etc... It can be used in a multi-scale modelling strategy as a transition from ab initio to large-scale finite element modelling (see Fig. 2).
|Fig. 3: The capabilities of TB_Sim.|
The capabilities of TB_Sim are summarized on Fig. 3. In particular, TB_Sim features:
The code is parallelized for OpenMP and MPI architectures. It can also make use of graphics cards (GPU) accelerators. TB_Sim has received in 2012 the third prize in the Bull-Fourier contest (high performance computing) for its parallel performances.
Coordinator and contact person:
|Fig. 4: (left) The electron (a) and hole (b) energy levels in InAs/InP nanowire heterostructures with radius R=10 nm as a function of the thickness tInAs of the InAs layer. (right) The corresponding conduction band wave functions for tInAs=4 nm and tInAs=16 nm. From Y. M. Niquet and D. Camacho Mojica, "Quantum dots and tunnel barriers in InAs/InP nanowire heterostructures: Electronic and optical properties", Phys. Rev. B 77, 115316 (2008).|
|Fig. 5: (top) (a) Density of states of an ideal (dashed line) and boron-doped graphene sheets for several boron concentrations Cd. (b, c) Local density of states on a boron and nitrogen impurity. (bottom) (a) Semiclassical conductivity at room temperature as a function of the carrier energy and Cd. Dotted lines correspond to the zero temperature limit. (b) Semiclassical conductivities for electrons and holes as a function of the carrier density and for Cd=0.5%. From A. Lherbier, X. Blase, Y. M. Niquet, F. Triozon and S. Roche, "Charge transport in chemically doped 2D graphene", Phys. Rev. Lett. 101, 036808 (2008).|
Electronic structure and transport properties of Si nanotubes.
J. Li, T. Gu, C. Delerue and Y. M. Niquet,
Journal of Applied Physics 114, 053706 (2013).
Residual strain and piezoelectric effects in passivated GaAs/AlGaAs core-shell nanowires.
M. Hocevar, L. T. T. Giang, R. Songmuang, M. den Hertog, L. Besombes, J. Bleuse, Y. M. Niquet and N. T. Pelekanos,
Applied Physics Letters 102, 191103 (2013).
Highly defective graphene: A key prototype of two-dimensional Anderson insulators.
A. Lherbier, S. Roche, O. A. Restrepo, Y. M. Niquet, A. Delcorte and J. C. Charlier,
Nano Research 6, 326 (2013).
Performances of strained nanowire devices: Ballistic versus scattering-limited currents.
V. H. Nguyen, F. Triozon, F. D. R. Bonnet and Y. M. Niquet,
IEEE Transactions on Electron Devices 60, 1506 (2013).
Size dependence of the exciton transitions in colloidal CdTe quantum dots.
E. Groeneveld, C. Delerue, G. Allan, Y. M. Niquet and C. de Mello Donega,
Journal of Physical Chemistry C 116, 23160 (2012).
mobility in strained Ge nanowires.
Y. M. Niquet and C. Delerue,
J. Appl. Phys. 112, 084301 (2012).
of strains on the mobility in silicon nanowires.
Y. M. Niquet, C. Delerue and C. Krzeminski,
Nano Letters 12, 3545 (2012).
state of GaN nanodisks in AlN nanowires studied by medium energy ion
D. Jalabert, Y. Curé, K. Hestroffer, Y. M. Niquet and B. Daudin,
Nanotechnology 23, 425703 (2012).
Boron-doped graphene field-effect transistors: A route toward
P. Marconcini, A. Cresti, F. Triozon, G. Fiori, B. Biel, Y. M. Niquet, M. Macucci and S. Roche,
ACS Nano 6, 7942 (2012).
negative differential conductance in graphene tunneling
V. H. Nguyen, Y. M. Niquet and P. Dollfus,
Semicond. Sci. Technol. 27, 105018 (2012).
properties of graphene containing structural defects.
A. Lherbier, S. M. M. Dubois, X. Declerck, Y. M. Niquet, S. Roche and J. C. Charlier,
Physical Review B 86, 075402 (2012).
of a large valley-orbit splitting in silicon with two-donor
B. Roche, E. Dupont-Ferrier, B. Voisin, M. Cobian, X. Jehl, R. Wacquez, M. Vinet, Y. M. Niquet and M. Sanquer,
Physical Review Letters 108, 206812 (2012).
mobility and variability in gate-all-around silicon nanowires.
Y. M. Niquet, H. Mera and C. Delerue,
Applied Physics Letters 100, 153119 (2012).
atomistic simulations of phonon-limited mobility of electrons and
holes in <001>, <110> and
<111>-oriented Si nanowires.
Y. M. Niquet, C. Delerue, D. Rideau and B. Videau,
IEEE Transactions on Electron Devices 59, 1480 (2012).
offsets, wells, and barriers at nanoscale semiconductor
Y. M. Niquet and C. Delerue,
Physical Review B 84, 075478 (2011).
graphene with structural defects: Elastic mean free path, minimum
conductivity, and Anderson transition.
A. Lherbier, S. M. M. Dubois, X. Declerck, S. Roche, Y. M. Niquet and J. C. Charlier,
Physical Review Letters 106, 046803 (2011).
modeling of electron-phonon coupling and transport properties in
n-type  silicon nanowires.
W. Zhang, C. Delerue, Y. M. Niquet, G. Allan and E. Wang,
Physical Review B 82, 115319 (2010).
impurity scattering and mobility in gated silicon nanowires.
M. P. Persson, H. Mera, Y. M. Niquet, C. Delerue and M. Diarra,
Physical Review B 82, 115318 (2010).
structural properties of GaN/AlN core-shell nanocolumn
K. Hestroffer, R. Mata, D. Camacho, C. Lecrere, G. Tourbot, Y. M. Niquet, A. Cros, C. Bougerol, H. Renevier and B. Daudin,
Nanotechnology 21, 415702 (2010).
capacitance of narrow band gap metal-oxide-semiconductor
E. Lind, Y. M. Niquet, H. Mera and L. E. Wernersson,
Applied Physics Letters 96, 233507 (2010).
effect in GaN/AlN nanowire heterostructures: Influence of strain
relaxation and surface states.
D. Camacho and Y. M. Niquet,
Physical Review B 81, 195313 (2010).
transport in graphene nanoribbons: effects of edge reconstruction
and chemical reactivity.
S. Dubois, A. Lopez-Bezanilla, A. Cresti, F. Triozon, B. Biel, J.-C. Charlier and S. Roche,
ACS Nano 4, 1971 (2010).
strain relaxation in GaN/AlN nanowire superlattice.
O. Landré, D. Camacho, C. Bougerol, Y. M. Niquet, V. Favre-Nicolin, G. Renaud, H. Renevier and B. Daudin,
Physical Review B 81, 153306 (2010).
of strain and stacking faults in single nanowires using Bragg
coherent diffraction imaging.
V. Favre-Nicolin, F. Mastropietro, J. Eymery, D. Camacho, Y. M. Niquet, B. M. Borg, M. E. Messing, L. E. Wernersson, R. E. Algra, E. P. A. M. Bakkers, T. H. Metzger, R. Harder and I. K. Robinson,
New Journal of Physics 12, 035013 (2010).
modeling and characterization of quasi-ballistic transport in
nanometer sized field effect transistors: from TCAD to atomistic
S. Roche, T. Poiroux, G. Lecarval, S. Barraud, F. Triozon, M. Persson and Y. M. Niquet,
International Journal of Nanotechnology 7, 348 (2010).
of Keating's valence force field model to non-ideal wurtzite
D. Camacho and Y. M. Niquet,
Physica E 42, 1361 (2010).
structural properties of GaN insertions in GaN/AlN nanocolumn
C. Bougerol, R. Songmuang, D. Camacho, Y. M. Niquet, R. Mata, A. Cros and B. Daudin,
Nanotechnology 20, 295706 (2009).
induced mobility gaps in graphene nanoribbons: a route for upscaling
B. Biel, F. Triozon, X. Blase and S. Roche,
Nano Letters 9, 2725 (2009).
functionalization effects on armchair graphene nanoribbon
A. Lopez-Bezanilla, F. Triozon and S. Roche,
Nano Letters 9, 2537 (2009).
nanotube chemistry and assembly for electronic devices.
V.Derycke, S.Auvray, J.Borghetti, C.-L.Chung, R.Lefèvre, A.Lopez-Bezanilla, K.Nguyen, G.Robert, G.Schmidt, C.Anghel, N.Chimot, S.Lyonnais, S.Streiff, S.Campidelli, P.Chenevier, A.Filoramo, M. F.Goffman, L.Goux-Capes, S.Latil, X.Blase, F.Triozon, S.Roche and J.-P.Bourgoin,
Comptes-Rendus Physique 10, 330 (2009).
simulation of carbon nanotube devices.
C. Adessi, R.Avriller, X.Blase, A.Bournel, H.Cazin d?Honincthun, P.Dollfus, S.Frégonèse, S.Galdin-Retailleau, A.López-Bezanilla, C.Maneux, H.Nha Nguyen, D.Querlioz, S.Roche, F.Triozon and T.Zimmer,
Comptes-Rendus Physique 10, 305 (2009).
doping effects on charge transport in graphene nanoribbons.
B. Biel, X. Blase, F. Triozon and S. Roche,
Physical Review Letters 102, 096803 (2009).
of the chemical functionalization on charge transport in carbon
nanotubes at the mesoscopic scale.
A. Lopez-Bezanilla, F. Triozon, S. Latil, X. Blase and S. Roche,
Nano Letters 9, 940 (2009).
structure effects on the scaling properties of  InAs nanowire
E. Lind, M. Persson, Y. M. Niquet and L. E. Wernersson,
IEEE Transactions on Electron Devices 56, 201 (2009).
dependence of charge transport in disordered silicon nanowires.
M. P. Persson, A. Lherbier, Y. M. Niquet, F. Triozon and S. Roche,
Nano Letters 8, 4146 (2008).
transport in chemically doped 2D graphene.
A. Lherbier, X. Blase, Y. M. Niquet, F. Triozon and S. Roche,
Physical Review Letters 101, 036808 (2008).
tunnelling spectroscopy of cleaved InAs/GaAs quantum dots at low
A. Urbieta, B. Grandidier, J. P. Nys, D. Deresmes, D. Stiévenard, A. Lemaître, G. Patriarche and Y. M. Niquet,
Physical Review B. 77, 155313 (2008).
and polaronic effects induced by a metallic gate and a surrounding
oxide on donor and acceptor impurities in silicon nanowires.
M. Diarra, C. Delerue, Y. M. Niquet and G. Allan,
Journal of Applied Physics 103, 073703 (2008).
dots and tunnel barriers in InAs/InP nanowire
heterostructures:Electronic and optical properties.
Y. M. Niquet and D. Camacho Mojica,
Physical Review B 77, 115316 (2008).
transport length scales in silicon-based semiconducting
nanowires:Surface roughness effects.
A. Lherbier, M. P. Persson, Y. M. Niquet, F. Triozon and S. Roche,
Physical Review B. 77, 085301 (2008).
length scales in disordered graphene-based materials:Strong
localization regimes and dimensionality effects.
A. Lherbier, B. Biel, Y. M. Niquet and S. Roche,
Physical Review Letters 100, 036803 (2008).
and shape of epitaxial InAs/InP nanowires measured by grazing
incidence X-ray techniques.
J. Eymery, F. Rieutord, V. Favre-Nicolin, O. Robach, Y. M. Niquet, L. Fröberg, T. Mårtensson and L. Samuelson,
Nano Letters 7, 2596 (2007).
of a shell on the electronic properties of nanowire
Y. M. Niquet,
Nano Letters 7, 1105 (2007).
communication with quantum dots spins.
C. Simon, Y. M. Niquet, X. Caillet, J. Eymery, J. P. Poizat and J. M. Gérard,
Physical Review B 75, 081302(R) (2007).
energy of donor and acceptor impurities in semiconductor
nanowires:Importance of dielectric confinement.
M. Diarra, Y. M. Niquet, C. Delerue and G. Allan,
Physical Review B 75, 045301 (2007).
and optical properties of InAs/GaAs nanowire
Y. M. Niquet,
Physical Review B 74, 155304 (2006).
structure of semiconductor nanowires.
Y. M. Niquet, A. Lherbier, N. H. Quang, M. V. Fernandez-Serra, X. Blase and C. Delerue,
Physical Review B 73, 165319 (2006).
More publications and links to journal sites can be found here.
Last update: October 22, 2013.