Growth and optical properties of ultra-long single-crystalline α-Si₃N₄ nanobelts

Ultra-long single-crystalline α-Si₃N₄ nanobelts were synthesized by catalyst-assisted crystallization of polymer-derived amorphous silicon carbonitride (SiCN). The obtained nanobelts were characterized using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and selected-area electron diffraction. The results revealed that the α-Si₃N₄ nanobelts are 20 to 40 nm in thickness, 400-600 nm in width and a few hundreds of micrometers to several millimeters in length, and grow along either the [011] or the [100] direction. Intense visible photoluminescence was observed over a spectrum ranging from 1.65 to 3.01 eV, which can be attributed to defects in the α-Si₃N₄ structure.