Résumé
We report a low temperature and room temperature photoluminescence (PL) study of a series of two-dimensional arrays of holes and pillars in a triangular lattice arrangement, fabricated in a 1.8 mu m thick GaN/sapphire epilayer. The sample was patterned by electron beam lithography and reactive ion etching in a CH4/H-2 plasma. Such structures with periodic variation of the dielectric constant may give rise to photonic crystals that can create a range of forbidden frequencies called a photonic bandgap. We have used the PL peak to evaluate the damage introduced onto the semiconductor by the etching procedure, and to determine the magnitude of the relaxation of the strain in the GaN film. Theoretical computations predict the photonic bandgap positions for future experimental investigations.