Properties of bulk AlN grown by thermodecomposition of AlCl3•NH3

Self-nucleated bulk AlN crystals were grown by thermodecomposition of AlCl3.NH3 vaporized in the low-temperature zone of a two-zone furnace. X-ray diffraction of the AlN crystals show single lines with a small linewidth indicating high single-crystalline quality. Polarized Raman scattering experiments of these samples confirm the x-ray results based on the detection of a small linewidth for all allowed optical phonons. Low-temperature cathodoluminescence spectra show very sharp emission bands close to the optical band gap, which have been assigned to free-excitons A and B, and exciton-bound to shallow neutral impurity. The latter has a full width at half maximum smaller than 1.0 meV. (C) 2003 American Institute of Physics.