Large rectifying ratio and prefect spin-filtering effect in a zigzag SiC nanoribbon heterojuction with boron and nitrogen impurities

Based on a mono hydrogen-passivated zigzag SiC nanoribbon with width 4, we construct a heterojunction through different substitutional impurities. The left part of the heterojunction is boron-doped at the Si-edge of zigzag SiC nanoribbon, and the right part is nitrogen-doped at the C-edge. Our results show that boron and nitrogen doped zigzag SiC nanoribbons exhibit half-metallic features at ferromagnetic state, which provides the possibility to design spin nanodevices. By performing first-principle quantum transport calculations, spin-dependent transport properties in different magnetic configurations are studied. Current-voltage curves show perfect spin-filtering and negative differential resistance effects when the spin orientations of the two electrodes are opposite. In the parallel magnetization configuration of two electrodes, a strong rectifying behavior is observed and the maximum rectifying ratio reaches the order of 10(9). Through detailed analysis of two electrodes' band structures along with the transmission spectra, the interesting transport behaviors can be understood. Besides, the Bloch states of spin-polarized bands crossing the Fermi level can help us to understand the appearance of the negative differential resistance effect.