Cathodoluminescence of impurity-doped aluminium nitride films produced by reactive evaporation

Single-crystal films of AlN were fabricated on sapphire (0001) substrates by the reactive evaporation of aluminium in NH3 gas at 1050 °C. The cathodoluminescence spectra of AlN films doped with twenty different elements including manganese, copper, magnesium, niobium and zinc and of undoped films were measured in the wavelength region 250–900 nm at room temperature. The films doped with manganese and niobium show peaks at about 595 and 510 nm whereas the spectra of the films doped with zinc, copper and magnesium using partially ionized beams have peaks or shoulders at about 420 and 460 nm (these wavelengths do not depend on the species of the doping atoms) in addition to the peak at 370 nm observed for undoped films. The results are discussed in conjunction with those observed for single-crystal AlN slabs and AlN powder.