Selective growth of Boron nitride nanotubes by the plasma-assisted and iron-catalytic CVD methods

Abstract

Boron nitride nanotubes (BNNTs) were selectively synthesized on patterned bilayer (Fe/Al) catalysts by the plasma-assisted chemical vapor deposition (PACVD) method. The as-grown nanotubes comprise both coaxial and cup-stacking tubular structures. Optical transitions on cup-stacking BNNTs are investigated for the first time. The observed red-shift of free excitonic luminescence was attributed to the excitonic recombination in terms of defect trapping in the tube's surface. The O2 additives during the synthetic process were found to balance the excess H radicals that in turn enhance the growth yield of BNNTs. Moreover, our elemental mapping results provide direct evidence of the metal catalytic mechanism and the influence of the as-formed Al 2O3 underlayer. © 2009 American Chemical Society.