Oxygen behavior in aluminum nitride

The infrared lattice-vibration spectra of three polycrystalline samples of wurtzite AlN differing in their oxygen contamination have been studied by measuring the room-temperature reflectivity at near-normal incidence in the 400-3000 cm-1 frequency range using unpolarized light. A type of highly-contaminated-material reflectivity spectrum has been observed. Two-mode behavior has been observed at low oxygen concentration, one-mode behavior tends to be dominant when the oxygen concentration increases and only one-mode behavior has been observed at high oxygen concentration. Otherwise, a careful analysis of the data using the Kramers-Kronig technique and classical dispersion theory gives, in addition to the transverse and longitudinal mode frequencies, two in-band resonance modes attributed to oxygen point defects in AlN. Changes in the frequencies of these modes with oxygen concentration are interpreted as a transition in the oxygen accommodation defect as the concentration of oxygen increases. A model for the behavior of oxygen in AlN is proposed. © 2005 American Institute of Physics.