The dependence of Raman scattering on Mg concentration in Mg-doped GaN grown by MBE

Magnesium-doped GaN (GaN:Mg) films having Mg concentrations in the range 5 × 10¹⁸–5 × 10²⁰ cm⁻³ were fabricated by molecular beam epitaxy. Raman spectroscopy was employed to study the effects of Mg incorporation on the positions of the E₂ and A₁(LO) lines identifiable in the Raman spectra. For Mg concentrations in excess of 2 × 10¹⁹ cm⁻³, increases in the Mg concentration shift both lines to higher wave numbers. The shifts of the Raman lines reveal a trend towards compressive stress induced by incorporation of Mg into the GaN films. The observed correlation between the Mg concentration and the Raman line positions establish Raman spectroscopy as a useful tool for optimizing growth of Mg-doped GaN. (papers)