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Proceedings Paper

Photoreflectance and Phototransmittance of Narrow Well Strained Layer In[sub]x[/sub]Ga[sub]1-x[/sub]As/GaAs Coupled Multiple Quantum Well Structures
Author(s): S. H. Pan; H. Shen; Z. Hang; F. H. Pollak; Weihua Zhuang; Qian Xu; A. P. Roth; R. A. Masut; C. Lacelle; D. Morris
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Paper Abstract

We have measured the photoreflectance (PR) spectra at 300K and 77K of two strained layer <001> InxGall-xAs/GaAs (x≈0.12) multiple quantum wells (MQW) with nominal well (Lz) and barrier (LB) widths of 50A/100A and 30A/100A, respectively, as deduced from the growth conditions. Phototransmittance at 77K of the latter sample has been studied. In both samples we have observed a number of features in the PR spectra corresponding to miniband dispersion (coupling between wells) of both confined and unconfined (above the GaAs barrier) transitions. The coupling between wells leads to different transition energies at the mini-Brillouin zone center (Γ) and edge (π) along the growth direction. This is the first observation of unconfined features and miniband dispersion in this system. Even though our samples have fairly wide barriers (LB ≈100A) the coupling between wells is an important effect because of the relatively small confinement energies for x≈0.12. Using the envelope function approach we have calculated the various transition energies taking into account both strain and quantum well effects, including miniband disper-sion. Good agreement with experiment is found for a heavy-hole valence band discontinuity of 0.3±0.05 and LZ/LB = 52±3A/105±5A(x=0.11±0.01) and 32±3A/95±5A(x=0.12±0.01) for the two samples, respectively. The In composition and well/barrier widths are thus in good agreement with the growth conditions. Although the symmetric component of the fundamental light-hole to conduction band transition is a strong feature, the small observed amplitude of the antisymmetric component for both samples is evidence for the type II nature of the light-hole to conduction band transitions.

Paper Details

Date Published: 18 August 1988
PDF: 9 pages
Proc. SPIE 0943, Quantum Well and Superlattice Physics II, (18 August 1988); doi: 10.1117/12.947309
Show Author Affiliations
S. H. Pan, Brooklyn College of the City University of New York (United States)
H. Shen, Brooklyn College of the City University of New York (United States)
Z. Hang, Brooklyn College of the City University of New York (United States)
F. H. Pollak, Brooklyn College of the City University of New York (United States)
Weihua Zhuang, Chinese Academy of Sciences (China)
Qian Xu, Chinese Academy of Sciences (China)
A. P. Roth, National Research Council of Canada (Canada)
R. A. Masut, National Research Council of Canada (Canada)
C. Lacelle, National Research Council of Canada (Canada)
D. Morris, National Research Council of Canada (Canada)

Published in SPIE Proceedings Vol. 0943:
Quantum Well and Superlattice Physics II
Federico Capasso; Gottfried H. Doehler; Joel N. Schulman, Editor(s)

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