Spectroscopic Determination of the Bandgap Crossover Composition in MBE-Grown AlxGa1-xAs

Brian Fluegel, Kirstin Alberi, John Reno, Angelo Mascarenhas

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3 Scopus Citations


The aluminum concentration dependence of the energies of the direct and indirect bandgaps arising from the Γ and Χ conduction bands are measured at 1.7K in the semiconductor alloy AlxGa1-xAs. The composition at which the bands cross is determined from photoluminescence of samples grown by molecular-beam epitaxy very close to crossover at x ≈ 0.4. The use of resonant laser excitation and the improved sample linewidth allows excitation intensities as low as 10-2 W/cm2, giving a precise determination of the bound exciton transition energies and their Γ and Χ crossover. Photoluminescence excitation spectroscopy is then used to measure the binding energies of the donor-bound excitons and the Γ free exciton binding energy. After correcting for the Γ- and Χ-dependence of these quantities, the crossover of the bandgap is determined to be at x = 0.401 and E = 2.086 eV.

Original languageAmerican English
Article number042402
Number of pages4
JournalJapanese Journal of Applied Physics, Part 2: Letters
Issue number4
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015 The Japan Society of Applied Physics.

NREL Publication Number

  • NREL/JA-5K00-63469


  • AlGaAs
  • photoluminescence


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