Optical properties of single-crystalline Wurtzite aluminum nitride nanowires

We have investigated the luminescence properties of single-crystalline wurtzite AlN nanowires by electron and photon excitation measurements, such as cathodoluminescence and photoluminescence. Band to band excitonic feature at 6.12 eV was first observed at room temperature in this study. Two typical defect band related transmissions around 3.0 eV and 4.85 eV were also observed, which are due to the radioactive recombination processes involving oxygen impurity and Al vacancies. The wurtzite AlN nanowires were grown on sapphire (0002) substrates by catalyst-assisted chemical vapor deposition. The morphology and structure were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman analysis.