Optical activation behavior of ion implanted acceptor species in GaN

Ion implantation is used to investigate the spectroscopic properties of Mg, Be, and C acceptors in GaN. Activation of these species is studied using l ow temperature photoluminescence (PL). Low dose implants into high quality undoped hydride vapor phase epitaxial (HVPE) material are used in conjuncti on with high temperature (1300 degreesC) rapid thermal anneals to obtain hi gh quality spectra. Dramatic, dose-dependent evidence of Mg acceptor activa tion is observed without any co-implants, including a strong, sharp neutral Mg acceptor-bound exciton and strong donor-acceptor pair peaks. Variable t emperature measurements reveal a band-to-acceptor transition whose energy y ields an optical binding energy of 224 meV. Be and C implants yield only sl ight evidence of shallow acceptor-related features and produce dose-correla ted 2.7 eV FL, attributed to residual implantation damage. Their poor optic al activation is tentatively attributed to insufficient vacancy production by these Lighter ions. Clear evidence is obtained for donor-Zn acceptor pai r and acceptor-bound exciton peaks in Zn-doped HVPE material.