Optical effects of interdiffusion in GaAs/AlAs heterostructures: Atomic scale calculations

14 October 1996

journal article
Published by AIP Publishing in Applied Physics Letters

Vol. 69 (16) , 2423-2425
https://doi.org/10.1063/1.117658

Abstract

We investigate the effects of atomic interdiffusion in the optical properties of AlAs/GaAs quantum wells through tight-binding model calculations. Ensembles of supercells, each cell containing up to ∼104 atoms with periodic boundary conditions, are used to simulate the heterostructures. The oscillator strength f of optical transitions at the absorption threshold is calculated as a function of the quantum-wells width W and the diffusion length L. As L increases, f undergoes a discontinuous transition to zero, indicating indirect-gap behavior for L larger than a critical value of the diffusion length. A unified behavior of f as a function of L/W1.7 is found. This permits relating optical properties to structural properties through simple fitting formulas.

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