Signature of GaN-AlN quantum dots by nonresonant Raman scattering

Stackings of GaN quantum dots embedded in an AlN matrix, constituting perio dic 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 sam ple with approximately the same composition has been also recorded. The dif ferences evidenced between these spectra give evidence for separate signatu res of quantum dots and spacers of the multilayered structure. The mean (bi axial) strain in GaN dots and AlN spacers has been deduced from the measure d phonon frequencies. (C) 2000 American Institute of Physics. [S0003-6951(0 0)03937-1].