Determination of Al molar fraction in AlxGa1-xN films by Raman scattering

Raman scattering spectra were observed for a series of AlxGa1−xN film samples to evaluate the Al molar fraction x from phonon frequencies using published data for calibration. Comparison with a precise quantitative measurement of x by electron-probe microanalysis (EPMA) showed systematic deviations from the Raman analysis up to about 6 ∼ 15%. The molar fraction was also deduced by x ray diffraction (XRD), assuming elastic deformation of the lattice and Vegard’s law for the lattice constant. The XRD analysis agreed well with that of EPMA to suggest that the Raman analysis is sensitively affected by lattice distortion due to residual stress.