Cathodoluminescence depth profiling of ion-implanted GaN

Cathodoluminescence (CL) spectroscopy shows that even relatively low-dose keV light-ion bombardment (corresponding to the generation of ∼5 × 10¹⁹ vacancies/cm³) of wurtzite GaN results in a dramatic quenching of visible CL emission. Postimplantation annealing at temperatures up to 1050°C generally causes a partial recovery of measured CL intensities. However, CL depth profiles indicate that, in most cases, such a recovery results from CL emission from virgin GaN, beyond the implanted layer due to a reduction in the extent of light absorption within the implanted layer. In this case, CL emission from the implanted layer remains completely quenched even after such an annealing. These results show that an understanding of the effects of ion bombardment and postimplantation annealing on luminescence generation and light absorption is required for a correct interpretation of luminescence spectra of GaN optically doped by keV ion implantation.