Raman Scattering and X-Ray Diffraction Study of Neutron Irradiated GaN Epilayers

Neutron irradiation induced defects and their effects on the carrier concentration of GaN epilayers are investigated with Raman scattering and X-ray diffraction techniques. Relative to the as-grown sample, the neutron-irradiated samples exhibit a clear variation in the position and lineshape of the A 1 (LO)-mode Raman peak as well as in the full-width at half-maximum height (FWHM) of the XRD rocking curves. Careful curve fitting and adequate calculations give the carrier concentrations of the irradiated GaN. It is found that the defects induced by neutron irradiation act as carrier trap centres which capture the electron carriers so that the carrier concentration of the irradiated GaN is reduced