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PRODID:UW-Madison-Physics-Events
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UID:UW-Physics-Event-1224
DTSTART:20080904T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260422T200520Z
LAST-MODIFIED:20080903T133119Z
LOCATION:5310 Chamberlin
SUMMARY:Multi-scale modeling of nano-devices\, R. G. Herb Condensed Ma
 tter Seminar\, Paul von Allmen\, Jet Propulsion Lab (Pasadena\, CA)
DESCRIPTION:Paul von Allmen and Trinh Vo<br>
\nSeungwon Lee\, Fabiano 
 Oyafuso and Gian Franco Sacco<br>
\nNASA - Jet Propulsion Laboratory<b
 r>
\nCalifornia Institute of Technology<br>
\n<br>
\nThe modeling of n
 ano-scale devices requires simulation capabilities at length scales th
 at span many orders of magnitude\, precluding the use of a single mode
 ling approach. At one end\, the electrodes have significant features a
 t the micron scale\, and at the other end\, the electronic wavefunctio
 ns are defined at the sub-nanometer scale. We have been integrating a 
 hierarchy of approaches\, for the calculation of the electronic struct
 ure and the lattice dynamics\, into a package that can for example com
 pute the effect of varying the electrode potential on atomic-level pro
 perties in realistic device structures. The electrostatic potential is
  obtained from a finite element solution of Poisson's equation. The ch
 arge density is described at 4 levels of decreasing scale: the semicla
 ssical approach\, the effective mass approximation\, the parameterized
  tight-binding method\, and first principles density functional theory
 . The lattice dynamics is described with valence force fields for larg
 e systems and density function theory at finer levels. The coupling wi
 th the electromagnetic field is described with a density matrix approa
 ch or the Keldysh formalism. This talk will give an overview of the me
 thods available at JPL and give a few illustrative examples\, such as 
 the modeling of spin qubits in Si/SiGe quantum dots\, and transport pr
 operties in Si and SiGe nanowires.
URL:https://www.physics.wisc.edu/events/?id=1224
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