AlxGa1−xAs alloys undergo a direct‐to‐indirect gap transition when the Al concentration x is increased, or when hydrostatic pressure P is applied to a direct‐gap sample of fixed composition. It is usually assumed that either hydrostatic pressure or alloying produce a Γ–X conduction band crossing responsible for the change in the nature of the gap. A critical discussion regarding this widely adopted criterion for the direct‐to‐indirect gap transition is presented. Alloying and pressure effects in the electronic properties of AlxGa1−xAs are determined through the small crystal approach with a 64‐site basic cluster. Finite‐size effects are discussed. The photoluminescence emission intensity is calculated as a function of x and P, and physically reliable criteria for the transition from the direct‐to‐indirect gap regimes based on these results are proposed. A critical concentration consistent with experimental results associated to this change of regime is obtained from our data.
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10 February 1992
Research Article|
February 10 1992
Physical criteria for the direct‐to‐indirect gap crossover in AlxGa1−xAs alloys
R. B. Capaz;
R. B. Capaz
Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Cx Postal 38071, 22452 Rio de Janeiro, RJ, Brazil
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J. P. von der Weid;
J. P. von der Weid
Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Cx Postal 38071, 22452 Rio de Janeiro, RJ, Brazil
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Belita Koiller
Belita Koiller
Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Cx Postal 38071, 22452 Rio de Janeiro, RJ, Brazil
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Appl. Phys. Lett. 60, 704–706 (1992)
Article history
Received:
October 04 1991
Accepted:
November 25 1991
Citation
R. B. Capaz, J. P. von der Weid, Belita Koiller; Physical criteria for the direct‐to‐indirect gap crossover in AlxGa1−xAs alloys. Appl. Phys. Lett. 10 February 1992; 60 (6): 704–706. https://doi.org/10.1063/1.106543
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