Investigation of luminescence from Dy3+ in AlN

The preparation of powder samples of aluminum nitride activated by dysprosium, AlN/Dy3+, was achieved for the first time using a low-temperature, solution-based approach. Aqueous solutions of aluminum and dysprosium nitrates was first converted to hydroxides and then to ammonium-metal hexafluorides (Al1-xDyx(NH4)(3)F-6. Finally, this complex ammonium salt was converted to finely divided powders of Al1-xDyxN via a pyrolysis reaction in a high-purity ammonia flow inside a tubular quartz furnace at 900 degrees C. The phase purity and crystallinity of the material were determined using X-ray diffraction and energy dispersive spectroscopy. The intraconfigurational f-f transitions of Dy3+ were investigated using photoluminescence (PL) and photoluminescence excitation (PLE) measurements. The excited states of Dy3+ in this large-gap nitride were identified from a careful analysis of PL and PLE results. It was also observed from the PLE measurements that the Dy3+ ions in this host are excited through energy transfer from both the excited state of the host lattice and defects. Measurements using site-selective spectroscopy suggest multiple sites for Dy3+ ions in AlN. A theoretical model describing the excitation process and saturation of excited states of Dy3+ at higher intensity of the exciting radiation is also proposed. (c) 2006 The Electrochemical Society.