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Structural, electronic and transport properties of quantum wires

June 9, 2008 to June 12, 2008

Location : CECAM-ENS, Lyon, France

Details
Participants
Abstracts
 

Organisers

  • Riccardo Rurali (The Institute of Materials Science of Barcelona, Spain)
  • Mads Brandbyge (DTU Nanotech, Technical University of Denmark, Denmark)
  • Xavier Blase (CNRS-LPMCN and University of Lyon 1, France)

Supports

   CECAM

   Psi-k

   COST - MolSimu

Description

The study of semiconducting nanowires is one of the most rapidly growing research areas in materials science and nanotechnology. Like carbon nanotubes, nanowires represent an excellent test-bed of how the quantum effects determine their geometric and electronic structure and, especially, their electron transport properties.
With the continuous miniaturization of electronic devices the search for building blocks of future molecular electronics application have attracted a great interest and nanowires seem to be one of the most promising alternative. The great advantage that they present over carbon nanotubes is that they are invariantly semiconducting, while, as it is well known, carbon nanotubes are metallic or semiconducting depending on their chirality that, to date, cannot be controlled at growth time. This is an essential feature for the design and realization of nanoelectronics applications, which require basic components that are semiconductors. Hence, not only nanowires can be used as interconnections between different components, but they can also directly operate as the active region of the device and several examples of (nano)transistors have been demonstrated.
However, an exhaustive physical understanding of many fundamental issues, such as the influence of the structure on the conducting properties, the role of surface conduction or defect scattering, is still lacking. A crucial mechanism like the contribution of extrinsic carriers (those provided by dopants) to the conduction, for instance, is far to be fully understood in systems of low dimensionality and nanoscopic sizes like nanowires and basic questions such as the radial localization of impurities, their ionization energy in the confined nanowire geometry, and their ability to trap states, are still largely unanswered. The difficulties inherent to the density functional theory to calculate excitation energies are a serious difficulty to address part of these questions.
The role of theoretical modeling and simulation is extraordinarily important, since many of the properties of nanowires only difficultly can be accessed experimentally. As a matter of fact, although the structure of the most common nanowires is reasonably well-know, thanks to several theoretical studies and experimental works, relatively little is known about the structure and the electronic properties in less conventional, but equally interesting situations, such as (i) heterostructures, lattice mismatch, strained structures, (ii) growth / deposition on surfaces (iii) stability, diffusion and electronic properties of defects and (iv) spin-transport in presence of magnetic impurities/leads. All these situations have the highest interest, and they are far to be satisfactorily understood.
Concerning silicon nanowires in particular, it must be underlined that wires grown along most of the crystallographic orientations exhibit a direct band-gap, while it is well-know that in bulk silicon is indirect. This circumstance opens a brand new research line which, obviously, has already attracted the interests of a large part of the nanoelectronics community: the realization of silicon-based optics and optoelectronics applications.

References

[1] J. Westwater and D. P. Gosain and S. Tomiya andS. Usui and H. Ruda <I>Growth of silicon nanowires via gold/silanevapor--liquid--solid reaction</I>, J. Vac. Sci. Technol. B <B>15</B> 554-557 (1997) <BR><BR> [2] Morales, Alfredo M. and Lieber, Charles M. <I>A Laser Ablation Method for the Synthesis ofCrystalline Semiconductor Nanowires</I>, Science <B>279</B> 208-211 (1998) <BR><BR> [3] Cui, Yi and Lieber, Charles M. <I>Functional Nanoscale Electronic Devices AssembledUsing Silicon Nanowire Building Blocks</I>, Science <B>291</B> 851--853 (2001) <BR><BR> [4] Fernando Patolsky and Charles M. Lieber <I>Nanowire nanosensors</I>, Materials Today <B>8</B> 20--28 (2005) <BR><BR> [5] Y. Li and F. Qian and J. Xiang and C. M. Lieber <I>Nanowire electronic and optoelectronic devices</I>, Materials Today <B>9</B> 18--27 (2006) <BR><BR> [6] Datta, S. <I>Quantum devices</I>, Superlatt. Microstruct. <B>6</B> 83--93 (1989) <BR><BR> [7] Mads Brandbyge and Jose-Luis Mozos andPablo Ordejon and Jeremy Taylor and Kurt Stokbro <I>Density-functional method for nonequilibriumelectron transport</I>, Phys. Rev. B <B>65</B> 165401 (2002) <BR><BR> [8] Thomas Frederiksen and Mads Brandbyge andNicolas Lorente and Antti-Pekka Jauho <I>Inelastic Scattering and Local Heating in AtomicGold Wires</I>, Phys. Rev. Lett. <B>93</B> 256601 (2004) <BR><BR> [9] Rurali, R. and Lorente, N. <I>Metallic and Semimetallic Silicon $langle 100rangle$ Nanowires</I>, Phys. Rev. Lett. <B>94</B> 026805 (2005) <BR><BR> [10] Singh, A.K. and Kumar, V. and Note, R. andKawazoe, Y. <I>Effects of Morphology and Doping on the Electronicand Structural Properties of HydrogenatedSilicon Nanowires</I>, Nano Lett. <B>6</B> 920--925 (2006) <BR><BR> [11] Fernandez-Serra, M.-V. and Adessi, Ch.and Blase, X. <I>Conductance, Surface Traps, and Passivation inDoped Silicon Nanowires</I>, Nano Lett. <B>6</B> 2674--2678 (2006) <BR><BR> [12] T. Vo and A. J. Williamson and G. Galli <I>First principles simulations of the structuraland electronic properties of silicon nanowires</I>, Phys. Rev. B <B>74</B> 045116 (2006) <BR><BR> [13] Stern, Eric and Klemic, James F. and Routenberg,David A. and Wyrembak, Pauline N. andTurner-Evans, Daniel B. and Hamilton, Andrew D.and LaVan, David A. and Fahmy, Tarek M. andReed, Mark A. <I>Label-free immunodetection with CMOS-compatiblesemiconducting nanowires</I>, Nature <B>445</B> 519--522 (2007) <BR><BR> [14] R. He and P. Yang <I>Giant piezoresistance effect in siliconnanowires</I>, Nat. Nanotechnol. <B>1</B> 42--46 (2006) <BR><BR> [15] Troels Markussen and Riccardo Rurali andAntti-Pekka Jauho and Mads Brandbyge <I>Scaling Theory Put into Practice: First-PrinciplesModeling of Transport in Doped Silicon Nanowires</I>, Phys. Rev. Lett. <B>99</B> 076803 (2007) <BR>


CECAM - Centre Européen de Calcul Atomique et Moléculaire
Ecole Polytechnique Fédérale de Lausanne, Batochime (BCH), 1015 Lausanne, Switzerland