A combination of coaxial impact ion scattering spectroscopy (CAICISS) and cross-sectional transmission electron microscopy (XTEM) was used to evaluate GaN films grown by metalorganic chemical vapor deposition. The polarity of the surface and the bulk of the buffer layers and high temperature layers could be evaluated with CAICISS and XTEM, respectively. Several buffer layers were grown and annealed at various temperatures on nitrided sapphire substrates prior to deposition of the high temperature (HT) layer. Most of the surfaces of the as-deposited buffer layers were found to have Ga (000 1) (+c) polarity. However, after annealing, the N (000 1) (-c) polarity was exposed due to evaporation of the film. This resulted in HT layers containing columnar and dome-shaped inversion domain with N (0001) (-c) polarity. The ratio of +c to -c polarity on the surface of the buffer layers was found by CAICISS to vary with the annealing time. It was found that the polarity of HT GaN films and the buffer layers was consistent using both CAICISS and XTEM.