Analysis of the local structure of AlN:Mn using X‐ray absorption fine structure measurements

Abstract

The local structure around the Mn atoms in MOCVD-grown AlN:Mn films which show Mn-related redorange photoluminescence with a 600nm-peak at room temperature was investigated using the X-ray absorption fine structure (XAFS) measurements. We found that Mn atoms occupy Al lattice sites in the AlN film and that the Mn ions have a charge between +2 and +3. From these results, we think that the redorange luminescence is caused by the transition of d-electrons in the Mn ions.1 Introduction Rare-earth doped AlN is a promising category of material for electroluminescent devices in visible wavelength region and spintronic devices with a high Curie temperature because of its wide bandgap, high melting point, and high luminescence efficiency. Among AlN materials, AlN:Mn shows red-orange photoluminescence (PL) and cathodoluminescence (CL) with a 600 nm-peak [1-3]. The possibility of constructing an electroluminescence (EL) device using this material has been suggested by the preliminary results on the EL operation of powder AlN:Mn [4,5]. Moreover, the redorange PL and EL from AlN:Mn films grown on a glass by MOCVD at the substrate temperature lower than the glass softening point of 600 ºC have been observed [6,7]. This means that it is possible to fabricate the large-area EL devices using AlN:Mn on glass.Although the technique of growing AlN:Mn has been developed over several years, the local atomic structure around Mn atoms in the films was not clearly determined. Because the structure strongly affects the Mn-related luminescence mechanism, determining the structure is very important for raising the quantum efficiency of AlN:Mn. Until now, it was thought from a theoretical analysis of the spectroscopic results [2] that Mn 4+ ions are the origin of red-orange PL, CL, and EL in AlN:Mn. To our knowledge, there is no other report on the charge of Mn and the local structure.

Manganese valence and coordination structure in Mn,Mg-codoped γ-AlON green phosphor

“…When Mn is accommodated in the tetrahedral structure, its emission spectrum exhibits green luminescence in oxide phosphors. On the other hand, orange emission is observed in AlN:Mn when Mn is at the tetrahedral site [25]. This suggests there is no preferential coordination with nitrogen around Mn in g-AlON as observed in the XANES spectra.…”

Characterization of AlN:Mn thin film phosphors prepared by metalorganic chemical vapor deposition

“…As to the origin of this emission, on the other hand, it is sill controversial. recently found that the Mn ions have a valence between 2+ and 3+ from the analysis using an X-ray absorption fine structure measurement [9]. Further studies are required to elucidate the origin of the emission.…”

Time‐resolved photoluminescence characterization of 2 eV band in AlN

“…Photoluminescence bands near 2 eV were observed earlier in AlN with below-bandgap excitation [8][9][10][11][12][13]. The bands were assigned to V Al -O N complexes [8], V N -Al i complexes [11], Mn Al or Cr Al impurities [12,13]. To characterize the 2 eV PL band we have performed temperaturedependent and time-resolved PL studies of AlN samples grown by molecular beam epitaxy at different conditions.…”