Effect of substrate position on the morphology of boron products by laser ablation

Single-crystalline boron nanobelts having rectangular cross sections with an -tetragonal structure and polycrystalline -rhombohedral boron films were fabricated using a laser ablation technique in a quartz glass tube chamber. The obtained products strongly depended on substrate position. The major products were boron nanobelts when the substrate was situated at the bottom of the tube with the pressure below 50 Pa in the temperature range from 700 °C to 900 °C. The boron product on a substrate at a side position in the tube always had a film morphology. The crystal structures of the obtained boron films, however, were amorphous under the conditions where nanobelts were observed. The products became well crystallized at pressures of 50 to 100 Pa at 900 °C. PACS 81.07.Bc; 81.15.Fg; 81.16.Mk; 79.20.Ds