Effect of heat preservation time on the micro morphology and field emission properties of La-doped SiC nanowires

Abstract

Lanthanum doped SiC nanowires (La-doped SiC NWs) were prepared using the chemical vapor reaction technique at different heat preservation times. Polycarbosilane was employed as a provider of both the Si and C elements. The characterization results suggested that the products were β-SiC. The nanowires straightened, the diameter of the nanowires became larger, and the content of La reduced with increasing heat preservation time. Meanwhile, the coating layer of SiO₂ obviously dwindled. The XPS spectrogram revealed that the existence of the element La in the product was in the form of a trivalent ion, La³⁺. The forbidden band width dropped from 1.37 to 0.8 eV after doping with La, which was calculated using Material Studio 4.2 software. When a heat preservation time of 120 min was used, the content of La had a minimum of 0.87 at%, and the turn-on field and the threshold field of the product were 1.2 and 5.0 V μm⁻¹, respectively. A synergetic influence mechanism was put forward to explain the effects of the morphology and the La content on the field emission (FE) properties of the La-doped SiC NWs. This work could act as a reference article for those researching FE properties of other one-dimensional nano-materials.