Evolution of the electronic states of coupled (In,Ga)As-GaAs quantum wells into superlattice minibands

Karen J. Moore, Geoffrey Duggan, Karl Woodbridge, Christine Roberts, Nicolas J. Pulsford, and Robin J. Nicholas
Phys. Rev. B 42, 3024 – Published 15 August 1990
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Abstract

We have used photoluminescence excitation (PLE) spectroscopy to study the evolution of the electronic states, and associated optical transitions, as the number of wells is increased from 2 to 5 to 20 in the strained (In,Ga)As-GaAs quantum-well system. The indium fraction in the wells was nominally 0.12. The PLE spectra of the two-well and five-well samples show strong Δn=0 exciton transitions and further features associated with transitions from confined states to continuum states. When a superlattice (SL) is formed, in the 20-well sample, we see momentum-conserving optical transitions at the mini-Brillouin-zone center and edge. We have also identified transitions associated with M1 critical points in the SL band structure. One of these is a Δn=0 exciton resonance below the saddle point while the other is a Δn≠0 exciton which has become allowed due to momentum mixing of the light- and heavy-hole bands in the plane perpendicular to the growth direction.

  • Received 19 March 1990

DOI:https://doi.org/10.1103/PhysRevB.42.3024

©1990 American Physical Society

Authors & Affiliations

Karen J. Moore, Geoffrey Duggan, Karl Woodbridge, and Christine Roberts

  • Philips Research Laboratories, Redhill, Surrey RH1 5HA, England

Nicolas J. Pulsford and Robin J. Nicholas

  • The Clarendon Laboratory, The University of Oxford, Parks Road, Oxford OX1 3PU, England

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Vol. 42, Iss. 5 — 15 August 1990

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