BYIn the present work we have investigated the influence of oxygen on the emission and excitation spectra of AlN. From the analysis of the spectra the ionization energies of the deep donor and acceptor levels were determined with respect to the conduction and valence band edges.Measurements were performed on crystalline powder of A1N:O. The concentration of oxygen in our samples was 0.73 to 4.85 w t s . On excitation of A1N:S samples by photons of energy 5.5 eV in addition to the previously described "visible" band the position and form of which depend on the conditions of excitation and observation /I/, a complex band in the UV region was observed /2/.Under steady excitation, the maximum of the UV band lies at E = 4.2 eV. The relative intensities of the components of this band substantially depend on the temperature.It has been shown previously /3/ that the emission and excitation spectra may be decomposed into elementary bands of half-width 0.46 eV. This method of decomposition and the parameters of elementary bands /2/ have been used in our analysis of the electroluminescence of an A1N:O diode /4/. In the "visible" part the energy Ee and half-width a r e the same in the photo-and cathodoluminescence spectra (bands 2 to 5 in Table 1). The parameters of the high energy components (6 to 9) of the electroluminescence spectrum in their turn have been used in the decomposition of the UV luminescence of AlN:O (Table 1).A s Table 1 shows the optical transitions (1 to 5 and 6 to 10) form two systems denoted by numbers I and I1 with equal relative positions of optical transitions within each system; the transition in the groups I and I1 are muEeTex = 1.48 e V (i = 1 to tually shifted by a constant energy 6 = E r ; r -i
5).The observation of two systems with five bands each in emission (and excitation) spectra indicates the existence of two final and five initial states.
The luminescence spectra, decay times, and EPR spectra of manganese activated aluminum nitride samples prepared under different conditions are studied. According to the preparation conditions manganese can be present in AlN as Mn4+ or Mn2+ ions with orange or green emission band, respectively. Efficient energy transfer from Mn2+ to Mn4+ ions takes place if both kinds of ions are present. At high concentration of manganese exceeding 0.005 wt% a new red emission band is observed, probably due to the pairs of interacting Mn4+ ions. The observed EPR spectra show HFS of Mn2+ ions and indicate that several nonequivalent positions of the Mn2+ ions with distorted cubic symmetry giving many possible values of the g‐factor are present in AlN.
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