Proton irradiation effects on HVPE GaN

GaNs grown by hydride vapor phase epitaxy (HVPE) were irradiated by protons with different fluences. The changes of surface topography of as-grown and irradiated samples were characterized by atomic force microscopy (AFM). The crystal quality and optical properties of GaN films were examined by the variations of the micro-Raman and photoluminescence (PL) spectra with proton fluence. It was observed that the surface became a little more rough after irradiation. The Raman spectra indicated that the strain of materials and carrier concentration were not affected by the proton injection. The full-width at half-maximum (FWHM) of E2 high phonon mode narrowed, which was consistent with the FWHM of PL near-band-edge emission (BE). The spectra of yellow luminescence and blue luminescence normalized to the intensity of BE demonstrated a little increase of Ga vacancy and a large decrease of ON, which may be the main reason for the change of optical properties.