Abstract

ABSTRACTWe report a photoluminescence (PL) and photoluminescence excitation (PLE) investigation of the deep iron acceptor in hexagonal GaN. Codoped samples give rise to a new zero-phonon line (ZPL) at 1.268 eV. The spectral shape of its phonon side band is very similar to that of the Fe3+ -spectrum. A lifetime of 2.6 ms was measured for this ZPL which indicates a spinforbidden transition. In contrast to isolated Fe3+, no Zeeman-splitting is observed. PLE spectra of the Fe3+ (4T1-6A1) zero-phonon line at 1.299 eV in semi-insulating GaN samples reveal intracenter excitation processes via excited states of the Fe3+ center. Three excited Fe3+ crystal field states at 1.299 eV (4T1), 2.01 eV (4T2), and 2.731 eV (4E) above the 6A1, ground state were identified. PLE spectroscopy for the 1.268 eV zero-phonon line reveals resonances at 2.3 eV and 2.65 eV. The 1.268 eV ZPL is tentatively attributed to a Fe-complex with a nearby donor.

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