Invited talk abstract

Recent data on shallow donors and acceptors in GaN will be discussed, with emphasis on optical experiments. The identification of optical signatures for shallow donors and acceptors, in particular bound exciton spectra, with the corresponding shallow impurity is still not final, and will be discussed. The main shallow impurities are Si, O, Be and Mg. Comparison will be made between results from HVPE and MOVPE grown GaN. Available magnetic resonance data will be discussed in connection with the optical data. The possible origin of some deep level spectra related to shallow dopants and intrinsic defects will briefly be discussed.