Excitation intensity dependence of photoluminescence spectra of SiGe quantum dots grown on prepatterned Si substrates: Evidence for biexcitonic transition

0384869 - FZÚ 2013 RIV US eng J - Journal Article
Klenovský, P. - Brehm, M. - Křápek, Vlastimil - Lausecker, E. - Munzar, D. - Hackl, F. - Steiner, H. - Fromherz, T. - Bauer, G. - Humlíček, J.
Excitation intensity dependence of photoluminescence spectra of SiGe quantum dots grown on prepatterned Si substrates: Evidence for biexcitonic transition.
Physical Review. B. Roč. 86, č. 11 (2012), "115305-1"-"115305-8". ISSN 1098-0121
Institutional research plan: CEZ:AV0Z10100521
Keywords : semiconductors nanocrystals * cyclotron resonance * uniaxial-stress * band alignment * Ge islands * germanium * wells * silicon * Si(001) * luminescence
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.767, year: 2012
http://prb.aps.org/abstract/PRB/v86/i11/e115305

The pumping intensity (I) dependence of the photoluminescence (PL) spectra of laterally two-dimensionally ordered SiGe quantum dots on Si(001) substrates was studied. The PL results from recombinations of holes localized in the SiGe quantum dots and electrons localized in the surrounding Si matrix. The analysis of the spectra revealed several distinct bands, attributed to phonon-assisted recombination and no-phonon recombination of the excitonic ground state and of the excited excitonic states, which all exhibit a linear I dependence of the PL intensity. At I>3 W.cm−2, additional bands with a quadratic I dependence appear in the PL spectra, resulting from biexcitonic transitions. These emerging PL contributions shift the composite no-phonon PL band of the SiGe quantum dots to higher energies. The observed transition energies are in good agreement with the exciton and biexciton energies calculated using the envelope function approximation and the configuration interaction method.
Permanent Link: http://hdl.handle.net/11104/0214353