Optical properties of GaAs/Al1xGaxAs quantum wells subjected to large in-plane uniaxial stress

G. Rau, A. R. Glanfield, P. C. Klipstein, N. F. Johnson, and G. W. Smith
Phys. Rev. B 60, 1900 – Published 15 July 1999
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Abstract

A comprehensive theoretical study of the effects of in-plane uniaxial stress on the excitonic absorption spectra of GaAs/AlxGa1xAs quantum wells is presented. In particular, stress is used to investigate optical features of excitonic mixing effects. State-of-the-art calculations of realistic excitonic absorption spectra under stress are performed that take valence-band mixing and the stress-induced anisotropy of the band structure into account. Two important aspects of in-plane uniaxial stress are identified each of which affects exciton mixing in a different way. On the one hand, the natural quantization direction gets rotated by stress from the confinement direction to the stress direction. This leads to a marked polarization dependence of the absorption spectrum, which can be explained within a simple model of single-particle zone-center states. On the other hand, uniaxial stress also allows the energy alignments of the valence states to be varied substantially. Thereby it is possible to influence the kp-related exciton mixing considerably, in particular between the lowest 1s light-hole exciton and the p continuum of the second heavy-hole exciton. This leads to the formation of doublet structures that reveal strong anticrossing behavior and have peculiar properties, which are best described within the framework of the Fano-Anderson model. Excellent agreement was achieved up to large stress values between our theoretical results and our experimental photoreflectance and photoluminescence results, with respect to the polarization dependence of the transition intensities and the stress dependence of the exciton energies. This clearly demonstrates the high accuracy of the calculations and provides conclusive evidence for the strong mixing effects that stress can cause.

  • Received 21 December 1998

DOI:https://doi.org/10.1103/PhysRevB.60.1900

©1999 American Physical Society

Authors & Affiliations

G. Rau, A. R. Glanfield, P. C. Klipstein, and N. F. Johnson

  • Clarendon Laboratory, Physics Department, Oxford University, Parks Road, Oxford OX1 3PU, United Kingdom

G. W. Smith

  • DERA, St. Andrews Road, Malvern, Worcestershire WR14 3PS, United Kingdom

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Vol. 60, Iss. 3 — 15 July 1999

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