Relationship between structure characteristic and blue luminescence in unintentional doped GaN layers

Properties of some GaN layers with different blue luminescence relative intensity were investigated by photoluminescence, Rutherford backscattering/channeling and double crystal X-ray diffraction, respectively. The surface minimum yields χmin of Rutherford backscattering/channeling and the FWHM of double crystal X-ray diffraction obviously increase with the increase of the intensity ratio of the blue luminescence to the band-edge emission. The blue luminescence is due to some intrinsic defects that can largely deteriorate the crystalline quality of GaN films. The luminescence mechanism of the blue luminescence in unintentional doped GaN films is different from that of the blue luminescence about 2.9 eV in GaN:Mg films.