1,017 research outputs found
Quantum-Dot Cascade Laser: Proposal for an Ultra-Low-Threshold Semiconductor Laser
We propose a quantum-dot version of the quantum-well cascade laser of Faist
et al. [Science {\bf 264}, 553 (1994)]. The elimination of single phonon decays
by the three-dimensional confinement implies a several order-of-magnitude
reduction in the threshold current. The requirements on dot size (10-20nm) and
on dot density and uniformity [one coupled pair of dots per (180nm)^3 with 5%
nonuniformity] are close to current technology.Comment: 8 pages, REVTEX 3.0, 3 compressed postscript figure
Accuracy of density functionals for molecular electronics: the Anderson junction
The exact ground-state exchange-correlation functional of Kohn-Sham density
functional theory yields the exact transmission through an Anderson junction at
zero bias and temperature. The exact impurity charge susceptibility is used to
construct the exact exchange-correlation potential. We analyze the successes
and limitations of various types of approximations, including smooth and
discontinuous functionals of the occupation, as well as symmetry-broken
approaches.Comment: 6 pages, 5 figures, submitted to Phys. Rev.
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