Zeeman spectroscopy of the internal transition 4T1 to 6A1 of Fe3+ ions in wurtzite GaN

Internal transitions of Fe3+ ions in wurtzite gallium nitride were analyzed by means of photoluminescence, Zeeman, and transmission spectroscopy in order to investigate the fine structure. Magnetic fields up to 14 T were applied perpendicular or parallel to the crystal c- axis, causing a characteristic splitting pattern of the luminescence related to the transition from the T-4(1) excited state to the (6)A(1) ground state of Fe3+. The complete Hamiltonian matrix is constructed taking into account the crystal field in cubic and trigonal symmetry, spin- orbit interaction, and the influence of external magnetic fields. Numerical solution yields the exact energy level scheme of the excited state (4)G of Fe3+ ions in GaN, which partly revises assumptions based on a qualitative treatment considering group theory only and invoking the influence of a Jahn-Teller effect. The coincidence of the calculated energy levels with the experimental data verifies the derived fine structure of the 3d metal ion. (C) 2015 AIP Publishing LLC.