Micro‐Raman spectroscopy of Si‐, C‐, Mg‐ and Be‐implanted GaN layers

We have carried out a systematic Raman study on Si‐, C‐, Mg‐ and Be‐implanted GaN layers. In the as‐implanted GaN layers, new Raman bands around 293–300, 360 and 666–671 cm−1 have appeared. From the phonon‐dispersion curves for hexagonal GaN, the 293–300 cm−1 and 666–671 cm−1 bands are assigned to the highest acoustic‐phonon branch and the optical‐phonon branch at the Brillouin zone boundaries, respectively. Several new modes at 168, 199, 320 and 346 cm−1 are also observed in the Raman spectra of Be‐implanted GaN after post‐implantation annealing and could be associated with Be‐related local vibrational modes in GaN. In the Si‐implanted GaN, we have also observed a new local vibrational mode at 612 cm−1 after thermal annealing.