Fabrication of crystal alpha-Si3N4/Si-SiOx core-shell/Au-SiOx peapod-like axial double heterostructures for optoelectronic applications

Novel crystal alpha-Si3N4/Si-SiOx core-shell/Au-SiOx peapod-like axial double heterostructural nanowires were obtained by directly annealing a Au covered SiO2 thin film on a Si substrate. Our extensive electron microscopic investigation revealed that the alpha-Si3N4 sections with a growth direction were grown first, followed by growth of the Si-SiOx core-shell sections and finally growth of the Au-SiOx peapod-like sections. Through a series of systematically comparative experiments, a temperature-dependent multi-step vapor-liquid-solid growth mechanism is proposed. Room temperature photoluminescence measurement of individual nanowires reveals two emission peaks (410 and 515 nm), indicating their potential applications in light sources, laser or light emitting display devices