Raman scattering and photoluminescence of Mg doped GaN films grown by molecular beam epitaxy

Raman, photoluminescence, and Hall measurements are reported for Mg doped GaN films grown by molecular beam epitaxy. The compressive and tensile stress determined by the Raman shift of the phonon lines is due to the growth conditions rather than the presence of Mg in the film. The photoluminescence peak of near band-to-band transitions is also shifted to larger (smaller) energies by the compressive (tensile) stress. The study of the longitudinal optical phonon of the A(1) branch shows that its Raman line shape is affected not only by phonon-plasmon interactions but by the crystalline quality of the film, as well.