We report what we believe to be the first preparation and optical spectroscopy of Er 3+ doped into bulk AlN ceramic. The material was prepared via hot press sintering of AlN with Er 2 O 3 and [NH 4 ][ErF 4 ], which yielded fully dense, translucent, hexagonal AlN. The Er 3+ concentration is a small fraction of a percent, and resides in multiple sites, with one type of center dominant. A number of the energy levels of Er 3+ are identified for this center. The temperature dependent fluorescence

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