Resonant Raman scattering in strained and relaxed InGaN/GaN multi-quantum wells

The effects of the composition and strain in InGaN/GaN multi-quantum wells on their phonon frequencies have been determined using resonant Raman scattering in a wide energy range. In pseudomorphic quantum wells a strong compensation of both effects occurs, resulting in the InGaN A(1)LO phonon frequency being almost independent on In concentration. In relaxed quantum wells the A(1)LO frequency is clearly below the GaN value and depends on the excitation energy, as reported in thick films. This variation, together with the resonance profile, gives a direct estimate of the, In concentration and its fluctuations. (C) 2005 American Institute of Physics.