Investigation of low-temperature cathodoluminescence mechanism of Er-doped GaN thick films by ion implantation

Er ions are implanted into the GaN thick films grown by hydride vapor phase epitaxy. The implantation energy is 200 keV and the implantation doses are 1 x 10(13), 1 x 10(14), 1 x 10(15), and 5 x 10(15) atom/cm(2), respectively. The effects of the implantation dose and annealing temperature on the GaN band-edge luminescence are investigated. The cathodoluminescence spectra from 82 to 323 K are measured for 1 x 10(15) atom/cm(2) implanted GaN annealed at 1100 degrees C. Luminescence peaks at 356, 362, 376, 390, and 414 nm are observed on the 82 K cathodoluminescence spectrum. When the temperature is increased to 150 K, the intensities of the 356 and 414 nm peaks are nearly unchanged and the 362, 376, and 390 nm peaks disappear. The intensity ratio of 538 nm (H-2(11/2) -> I-4(15/2)) and 559 nm (S-4(3/2) -> I-4(15/2)) is increased with the increase in temperature. We try to shed light on the above interesting phenomena.