Segregation, interface morphology, and the optical properties of GaAs/AlAs quantum wells: A theoretical study

Belita Koiller, R. B. Capaz, and H. Chacham
Phys. Rev. B 60, 1787 – Published 15 July 1999
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Abstract

We investigate optical signatures of interface segregation phenomena in epitaxially grown narrow quantum wells. Short-period step formation and segregation during growth are simulated via a generalized kinetic-limited segregation model that allows for combined vertical and lateral atomic exchanges with respect to the surface. Segregation always leads to more abrupt inverted (GaAs-on-AlAs) interfaces as compared to normal (AlAs-on-GaAs) interfaces, where a wider alloy region is present. The electronic structure of quantum wells is determined in the tight-binding approach applied to supercells (104atoms) with periodic boundary conditions. The atomic configurations are numerically generated according to the two-dimensional composition profiles obtained from the generalized kinetic-limited segregation model. Disorder is incorporated through an ensemble of such generated configurations, over which averaged electronic quantities are obtained. The correlation between the interface degree of roughness, alloying, and its optical properties is demonstrated. We show that segregation may improve the light-emission properties of quantum wells by reducing the roughness of stepped interfaces.

  • Received 19 May 1998

DOI:https://doi.org/10.1103/PhysRevB.60.1787

©1999 American Physical Society

Authors & Affiliations

Belita Koiller and R. B. Capaz

  • Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68.528, 21945-970, RJ, Brazil

H. Chacham

  • Departamento de Física, ICEx, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970, MG, Brazil

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Vol. 60, Iss. 3 — 15 July 1999

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