Mechanism for Low Temperature Growth of Boron Nitride Nanotubes

Selective growth of boron nitride nanotubes (BNNTs) was demonstrated by plasma-enhanced pulsed laser deposition (PE-PLD). Although PLD is a physical vapor deposition technique for the growth of boron nitride (BN) thin films, ion sputtering induced by the plasma can eliminate the formation of BN thin films and lead to the so-called total resputtering region, in which, a pure phase of BNNTs can be grown at 600-700 °C using Fe catalyst. These BNNTs can be grown at desired locations and have high structural orders with diameter ∼10-20 nm. In addition, we found that effective catalysts for the growth of these BNNTs should have both significant solubility of boron and relatively low sputtering yield. All of these observations can be summarized into a phase selective growth model that combining the vapor-liquid-solid (VLS) mechanism and the effect of ion sputtering.