Influence of growth temperature on the morphology and luminescence of Ga_2O_3:Mn nanowires

Mn doped –Ga_2O_3 nanowires have been obtained by a thermal evaporation method on a gallium oxide substrate. The growth temperature has been varied in the range 1300-1500 ºC. The morphology of the resulting structures has been found to depend on this temperature, as observed in the images obtained with scanning electron microscopy. The structures grown on the sample at 1500 ºC are both isolated microrods and interconnected rods. At lower temperatures, 1300 and 1400 ºC, nanowires with widths of about 100nm and stair-shaped microcrystals were found. Raman analysis demonstrates that both nanowires and microrods present the -Ga2O3 crystal structure. In addition, Mn related light emission has been found to depend on the growth temperature. The assessment of luminescence properties have been carried out by cathodoluminescence analysis. The results show an intense orange emission in the nanowires and green emission in the microrods. These bands are associated to the manganese ions incorporated into the gallium oxide crystal lattice