Signature of GaN-AlN quantum dots by nonresonant Raman scattering

Stackings of GaN quantum dots embedded in an AlN matrix, constituting periodic structures with a mean aluminum content in the 80%-90% range, have been investigated by Raman spectroscopy under excitation in the visible range, i.e., far from resonant conditions. For comparison, spectra of an alloy sample with approximately the same composition has been also recorded. The differences evidenced between these spectra give evidence for separate signatures of quantum dots and spacers of the multilayered structure. The mean (biaxial) strain in GaN dots and AlN spacers has been deduced from the measured phonon frequencies. (C) 2000 American Institute of Physics. [S0003-6951(00)03937-1].