Atomic-Scale Electronic Characterization of Defects in Silicon Carbide Nanowires by Electron Energy-Loss Spectroscopy

The atomic-level resolution of scanning transmission electron microscopy (TEM) is used for structural characterization of nanomaterials, but the resolution afforded by TEM also enables electronic characterization of defects in these materials through electron energy-loss spectroscopy (EELS). Here, the power of EELS is harnessed to characterize the local band gap of inclusion defects in hexagonal silicon carbide nanowires with a high density of stacking faults. The band gaps we extract from the EELS data align within 0.1 eV of expected values for hexagonal silicon carbide and stacking faults within hexagonal silicon carbide. These experiments show that individual cubic phase inclusions in hexagonal silicon carbide significantly alter the local electronic structure, in particular, the band gap, in contrast to the polarizability tensor that retains the characteristic signature of the global hexagonal crystal structure.