Tunable fabrication and photoluminescence property of SiC nanowires with different microstructures

Abstract

SiC nanowires including ultra-thin, hierarchical, bamboo-like, beaded-like and core-shell nanowires were successfully synthesized via carbothermal reduction method without using catalyst. The microstructures and diameter were controlled by reaction temperature ranging from 1500 to 1600 °C, holding time from 2 to 4 h and different raw materials. Notably, the diameter of ultra-thin SiC nanowires was ranging from 8 to 20 nm. Photoluminescence properties of obtained nanowires with unique microstructures were investigated at room temperature. It indicates that the primary emission peaks locate in the blue/violet band range of 350–500 nm with obvious blue shifts. Meanwhile, the luminescence mechanism of SiC nanowires is discussed in detail. The ultra-thin SiC nanowires exhibit the highest intensity because of the strong quantum confinement effect and the quasi-direct band gap. Due to the strong defects effect of twin segments, hierarchical and bamboo-like nanowires with high stacking faults and rough surface show higher intensity under 263 nm excitation. While beaded-like and core-shell nanowires with SiO2 shell and smooth surface exhibit a noticeable increase in the intensity under 318 nm excitation. This might be ascribed to the neutral oxygen vacancies and oxygen atoms.