Raman spectroscopic calibrations of phonon deformation potentials in wurtzitic AlN

A controlled biaxial stress field generated in a ball-on-ring configuration was applied on a thin hexagonal (0001)AlN film grown on (001)Si substrate, and the phonon deformation potential (PDP) constants of the A₁ (TO), E₂ (high), and A₁ (LO) Raman modes were retrieved from the respective spectral shifts. Measurements were done: (i) at given fixed locations upon increasing the externally applied load; and (ii) along spectral line scans performed at a fixed load. The reliability of the retrieved PDP values, in comparison with values previously reported in the literature, was examined by a further evaluation of the residual stress field stored in the AlN/Si system associated with the tip of a crack propagated from the corner of a pyramidal indentation. The PDP assessments were confirmed to be reliable owing to a close correspondence among stress intensity factors independently retrieved from different Raman bands.