Catalyst-assisted synthesis and growth mechanism of ultra-long single crystal α-Si3N4 nanobelts with strong violet–blue luminescent properties

Abstract

Ultra-long single crystal α-Si₃N₄ nanobelts were prepared by thermal chemical vapour deposition (CVD) method. Silicon vapour from the original solid silicon raw material was allowed to react with flowing nitrogen at 1450 °C on the carbon felt deposited with Ni(NO₃)₂. The as-prepared α-Si₃N₄ nanobelts were 40–60 nm thick, 200–300 nm wide, and up to several millimetres long. Their growth process was governed by the VLS base-growth and the VS tip-growth mechanisms. The former was responsible for the initial nucleation and proto-nanobelt (template) formation of α-Si₃N₄ and the subsequent growth along the [101] or [100] direction, and the latter for the additional growth at the tips. The synergistic function from these two growth mechanisms resulted in the formation of a large quantity of ultra-long α-Si₃N₄ nanobelts. An intense violet–blue visible photoluminescence (PL) of the as-synthesized α-Si₃N₄ nanobelts was observed at room temperature, which could be highly valuable for the future potential applications in optoelectronic nanodevices.