Premium
InGaAs/GaAs quantum wells and quantum dots on GaAs(11 n ) substrates studied by photoreflectance spectroscopy
Author(s) -
RojasRamirez J. S.,
YeeRendón C. M.,
CruzHernandez E.,
ContrerasGuerrero R.,
VazquezLopez C.,
MelendezLira M.,
LopezLopez M.
Publication year - 2007
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200673957
Subject(s) - quantum well , quantum dot , molecular beam epitaxy , heterojunction , indium , spectral line , spectroscopy , blueshift , condensed matter physics , chemistry , stark effect , materials science , molecular physics , epitaxy , photoluminescence , optoelectronics , optics , physics , nanotechnology , quantum mechanics , laser , layer (electronics)
Pseudomorphic InGaAs/GaAs quantum wells (QWs) and self‐assembled InAs quantum dots (QDs) were grown by molecular beam epitaxy (MBE) on GaAs(11 n )A substrates. Photoreflectance spectroscopy was employed to investigate the transitions in the heterostructures. The transitions in QWs have two contributions, a blue shift due to the compressive strain, and a red shift due to the quantum confined Stark effect produced by the piezoelectric field. A traditional theoretical interpretation of the QWs transitions employing a simple well model with sharp interfaces shows discrepancies with the experimental results. In order to satisfactorily explain the transitions we proposed to include segregation effects of Indium at the wells interfaces. The matrix transfer method was implemented to numerically solve the Schrödinger equation taking into account In segregation effects by including an asymmetric potential well with a profile depending on the details of the In incorporation. With segregation effects included, the calculated transitions fit very well the PR spectra. On the other hand, the transitions in self‐assembled QDs were obtained by fitting the PR spectra employing a first derivative line‐shape function. For n = 2, 4, 5, two functions were required to fit the spectra. For n = 3 only one function was required, in agreement with the more uniform QDs size distribution observed by atomic force microscopy on GaAs(113)A. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)