Stability investigation of cubic GaN films grown by metalorganic chemical vapor deposition on GaAs (001)

The thermal stability of cubic-phase GaN (c-GaN) films are investigated by photoluminescence (PL) and Raman scattering spectroscopy. C-GaN films are g rown on GaAs (001) substrates by metalorganic chemical vapor deposition. PL measurements show that the near-band-edge emissions in the as-grown GaN la yers and thermally treated samples are mainly from c-GaN. No degradation of the optical qualities is observed after thermal annealing. Raman scatterin g spectroscopy shows that the intensity of the E-2 peak from hexagonal GaN grains increases with annealing temperature for the samples with poor cryst al quality, while thermal annealing up to 1000 degrees C has no obvious eff ect on the samples with high crystal quality. (C) 1999 American Institute o f Physics. [S0003-6951(99)04719-1].