Effect of monatomic and molecular ion irradiation on time resolved photoluminescence decay in GaN

Optical effects induced in silicon-doped wurtzite (0001) GaN epilayers by keV monatomic and molecular ion irradiation were experimentally investigated. Results were analyzed together with data on structure defect formation. In all the cases under consideration, an increase in the collision cascade density (the cases of molecular and heavy atomic ion bombardment) enhances the stable damage accumulation rate and, accordingly, intensifies quenching of luminescence. The processes of PL suppression were theoretically considered as an increase of surface recombination rate of nonequilibrium photo-excited charge carriers due to production of stable damage at the irradiated subsurface layer. It is shown that carrier diffusion determines PL decay time shortening in the shallow implantation cases studied.