Raman Scattering Spectroscopy of Residual Stresses in Epitaxial AlN Films

High-crystalline-quality epitaxial films of wurtzite AlN were grown by metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE). The lattice strain of the films was analyzed by high-resolution X-ray diffraction and the E-2 (high)-phonon frequency was observed by Raman scattering. Data analysis for wide ranges of lattice strains and phonon-peak shifts yielded a precise biaxial stress coefficient of this phonon mode, -4.04 +/- 0.3 cm(-1)/GPa. Furthermore, the deformation potential constant was accurately determined from the biaxial stress coefficient. (C) 2011 The Japan Society of Applied Physics