Indium Distribution within In_xGa_(1-x)N Epitaxial Layers: A Combined Resonant Raman Scattering and Rutherford Backscattering Study

摘要

We report a Raman spectroscopy study performed at room temperature on In_xGa_(1-x)N epitaxial layers grown by metalorganic chemical vapour deposition on top of GaN/sapphire (0001) substrates. Resonant Raman measurements have been performed using excitation energies of 2.34, 2.54 and 3.02 eV. A shift of the A_1(LO) phonon mode frequency was observed under different excitation energies. This is interpreted with respect to the composition and strain variations within the sample. The A_1(LO) phonon line shape is analysed using a Spatial Correlation Model (SC). The structural parameters were determined by Rutherford backscattering spectrometry (RBS).