Bound excitons in GaN

• The electronic structure of bound excitons in GaN is discussed, with reference to available optical data. Emphasis is given to the neutral-donor and neutralacceptor spectra, which are the most prominent ones in the experimental photoluminescence data. Two dominant donor bound excitons are observed with photoluminescence lines just above 3.47 eV at 2 K in unstrained samples, tentatively associated with Si and O shallow donors. Several acceptor bound excitons are present, the most prominent one with a photoluminescence line at about 3.466 eV is tentatively assigned to the Mg acceptor. We attempt an explanation of the available data from magneto-optical experiments on this line in terms of a spin-like acceptor hole, as observed in independent magnetic resonance data. Characteristic deep emissions related to P and As doping are reported, they may be interpreted in terms of isoelectronic bound excitons. Excitons bound to structural defects in GaN are also briefly discussed.

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