Direct signature of strained GaN quantum dots by Raman scattering

We report on a Raman study of strained wurtzite GaN quantum dots embedded in AlN spacers. Various laser excitations between 2.33 and 3.81 eV were used, which allows for selective probing of the dots, through resonant enhancement of the Raman signal. A direct signature of the A1 (LO) and E2 phonons of the GaN dots has been obtained. The measured phonon frequencies show that the mean in-plane strain inside the GaN dots approaches the lattice mismatch between GaN and AlN.