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Stepwise evolution of Au nanocrystals from an octahedron to a truncated ditetragonal prism and rhombic dodecahedron was achieved by the polyol synthesis method.

Silicon carbide (SiC) devices have shown substantial promise in realizing ultrahigh-voltage and high power, and have been usually considered as a potential candidate for high radiation levels applications. However, in this work it is found that the SiC P-intrinsic-N (PiN) diodes are sensitive to the electron irradiation, which exerts significant influence on the device characteristics. The physical mechanisms behind these behaviors are studied by probing the production of point defects and the evolution of carrier lifetime in the SiC epilayers after irradiation. It is found that the forward current is significantly reduced by irradiation and the specific on-resistance monotonously increases with the increasing electron fluences, which is resulted from the deteriorated conductivity modulation effects in the epilayer due to the enhanced carrier recombination from the radiation induced deep-level defects, such as the carbon vacancy (V C ), silicon vacancy (V Si ) and V C +V Si complexes. Inversely, no significant change is observed in the reverse leakage current of 4H-SiC PiN diodes, and the breakdown voltage even slightly increases after electron irradiation, which are ascribed to the suppressed carrier generation arising from the point defects in 4H-SiC with a wide bandgap and the carrier-removal effects caused by the acceptor like point defects generated during irradiation, respectively.INDEX TERMS Silicon carbide, point defects, carrier lifetime, electron irradiation, PiN diodes.