Yellow and red luminescence in Mg-implanted GaN epitaxial films

X-ray diffraction (XRD), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and photoluminescence (PL) were applied to study yellow and red luminescence properties of as-grown and Mg-implanted n-type wurtzite GaN films grown on sapphire substrates by metal-organic chemical vapor deposition. The influence of different Mg-implanted fluences on yellow and red luminescence was studied. The as-grown GaN thin films exhibited intense broad yellow emission which reduces drastically after Mg ion implantation. A red luminescence band at approximately 750 nm appears when the Mg implantation fluence is low (1013 cm−2) whereas a yellow luminescence band suddenly increases at a Mg-implanted fluence of 1016 cm−2. The possible reasons of these phenomena are discussed.