Key Words:Field emission property; La-doping; N-doping; SiC nanowire; First-principles
Abstract:La- and N-doped SiC nanowires were prepared using a vapor-phase doping method and chemical vapor deposition method, respectively. The morphologies, element analysis, and crystal structures of the products were characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), high-resolution transmission electron microscope (HRTEM), X-ray energy dispersive spectrum (EDS), and X-ray diffraction (XRD). The field emission properties of the nanowires doped with different elements were tested by field emission measurements, and the results show that the turn on field (E-to) and threshold field (E-thr) of La-doped SiC nanowires are 1.2 and 5.2 V.mu m(-1), and those of N-doped SiC nanowires are 0.9 and 4.0 V.mu m(-1), respectively, these values are clearly lower than those of 2.3 and 6.6 V.mu m(-1) for undoped SiC nanowires. In addition, the density of states (DOS) and band structures of undoped, N-doped, and La-doped, SiC nanowires were also calculated using Castep of material studio on the basis of the first-principles. The results of the theoretical calculations suggest that the narrower gap may be attributed to the impurity energy level (La 5d or N 2p) generated near the Fermi level. Because of the narrower gap, electrons transfer from the valence band maximum (VBM) to conduction band minimum (CBM) need less energy, and this enhances the field emission property.
Volume:31
Issue:6
Translation or Not:no