Facile synthesis of α‐Si₃N₄ nanoneedles and their photoluminescence properties

Abstract

Needle-like α-Si 3 N 4 with unique structures has potential application in both field emission devices and tips for atomic force microscopes. Single-crystalline, α-Si 3 N 4 nanoneedles have been prepared by using an improved chemical vapor deposition (CVD) method at 1200°C for 3 hours. The phases, chemical composition, and microstructure of the as-prepared products were determined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) equipped with EDS. The as-synthesized products show a needle-like morphology with hundreds of micrometers in length and nanometer-featured tips. The nanoneedles show a α-Si 3 N 4 @SiOx core-shell heterostructure as characterized by TEM, with single-crystalline α-Si 3 N 4 core and an insulating amorphous silicon oxide shell. The growth of α-Si 3 N 4 nanoneedles corresponds to vapor-liquidsolid cap-growth and base-growth mechanism. Photoluminescence (PL) properties of the products were also characterized. An obvious emission peak at 400 nm under 254 nm UV excitation was observed. The nanoneedle morphology and photoluminescence properties of the products have potentials to be used in future optoelectronic nanodevices. K E Y W O R D SCVD, growth mechanism, nanoneedles, photoluminescence, α-Si 3 N 4 2374 | SHEN Et al.

α-Si3N4 dendrites and whiskers fabricated using electron irradiation technology

“…35 Because the α-Si 3 N 4 whiskers in this study are formed in the SiO liquid environment through the reaction of SiO and N atoms, the oxygen bonds including Si-O-Si and N-Si-O may exit in the whiskers, which can lead to the emission near 488 nm (2.54 eV). 13,36,37 The room-temperature PL spectrum of tree-like α-Si 3 N 4 dendrites is shown in Fig. S3.…”

“…During the past few decades, extensive efforts have been devoted to synthesizing high-quality Si 3 N 4 , and plenty of advanced synthesis technologies have been developed, including direct nitridation, 3 carbothermal reduction, 10 polymer precursor pyrolysis 11,12 and chemical vapor deposition. 13 Recently, single-crystalline Si 3 N 4 nanospheres with a smooth surface have been synthesized using a radio frequency thermal plasma system. 6 The Si 3 N 4 nanosphere exhibits high thermal conductivity, excellent thermal stability and low dielectric loss tangent.…”

“…15 Moreover, Si 3 N 4 nanowires and nanoribbons have also been synthesized, which exhibit super ductility and extraordinary optical properties. 4,13,[16][17][18] In addition, ear-like Si 3 N 4 dendrites can be formed by the reaction of SiO 2 /Fe composites and Si powders in N 2 atmosphere. 19 Nevertheless, most of the above fabrication methods are high energy-or time-consuming, and it is still a challenge to achieve the fabrication of high-quality Si 3 N 4 with different morphologies by the control of fabrication conditions.…”