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Title: Multiparticle states and the factors that complicate an experimental observation of the quantum coherence in the exciton gas of SiGe/Si quantum wells

The measured stationary and time-resolved photoluminescence is used to study the properties of the exciton gas in a second-order 5-nm-thick Si{sub 0.905}Ge{sub 0.095}/Si quantum well. It is shown that, despite the presence of an electron barrier in the Si{sub 0.905}Ge{sub 0.095} layer, a spatially indirect biexciton is the most favorable energy state of the electron–hole system at low temperatures. This biexciton is characterized by a lifetime of 1100 ns and a binding energy of 2.0–2.5 meV and consists of two holes localized in the SiGe layer and two electrons mainly localized in silicon. The formation of biexcitons is shown to cause low-temperature (5 K) luminescence spectra over a wide excitation density range and to suppress the formation of an exciton gas, in which quantum statistics effects are significant. The Bose statistics can only be experimentally observed for a biexciton gas at a temperature of 1 K or below because of the high degree of degeneracy of biexciton states (28) and a comparatively large effective mass (about 1.3m{sub e}). The heat energy at such temperatures is much lower than the measured energy of localization at potential fluctuations (about 1 meV). This feature leads to biexciton localization and fundamentally limits the possibilitymore » of observation of quantum coherence in the biexciton gas.« less
Authors:
; ; ;  [1] ;  [2] ; ; ;  [1]
  1. Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
  2. Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)
Publication Date:
OSTI Identifier:
22471937
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 121; Journal Issue: 6; Other Information: Copyright (c) 2015 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BINDING ENERGY; EFFECTIVE MASS; ELECTRONS; EMISSION SPECTRA; EXCITONS; FLUCTUATIONS; GERMANIUM SILICIDES; HOLES; LAYERS; LIFETIME; PHOTOLUMINESCENCE; QUANTUM WELLS; SILICON; TEMPERATURE RANGE 0000-0013 K; TIME RESOLUTION