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Optical properties of Si/Si0.87Ge0.13 multiple quantum well wires
Nanometer-scale wires cut into a Si/Si0.87Ge0.13 multiple quantum well structure were fabricated and characterized by using photoluminescence and photoreflectance at temperatures between 4 and 20 K. It was found that, in addition to a low-energy broadband emission at around 0.8 eV and other features normally observable in photoluminescence measurements, fabrication process induced strain relaxation and enhanced electron-hole droplets emission together with a new feature at 1.131 eV at 4 K were observed. The latter was further identified as a transition related to impurities located at the Si/Si0.87Ge0.13 heterointerfaces
Degeneracy of Ground State in Two-dimensional Electron-Lattice System
We discuss the ground state of a two dimensional electron-lattice system
described by a Su-Schrieffer-Heeger type Hamiltonian with a half-filled
electronic band, for which it has been pointed out in the previous paper [J.
Phys. Soc. Jpn. 69 (2000) 1769-1776] that the ground state distortion pattern
is not unique in spite of a unique electronic energy spectrum and the same
total energy. The necessary and sufficient conditions to be satisfied by the
distortion patterns in the ground state are derived numerically. As a result
the degrees of degeneracy in the ground state is estimated to be about
for with the linear dimension of the system.Comment: 2pages, 2figure
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