Cathodoluminescence study of widegap-semiconductor nanowires

Two kinds of widegap-semiconductor nanowires, Tb-doped AlN nanowire arrays on Si and freestanding BN nanowires, were fabricated by different catalyst-free methods. Well-aligned Tb-doped AlN nanowire arrays were grown on the Si (111) substrate by magnetron sputtering method. Free-standing BN nanowires were grown by heat-treatment of B-N-O precursor and graphite powders. The crystal structure of nanowires was characterized by using X-ray diffraction and transmission electron microscopy. Cathodeluminescence (CL) observation was performed with a field emission scanning electron microscope operating with an electron beam lower than 5 kV. CL spectra mapping as well as monochromatic CL imaging clearly revealed not only the variation of the luminescence spectra of different nanowires but also that along the single wire. Our results demonstrates the advantage of CL for the characterization of nanowires.