Electrical properties and spintronic application of carbon phosphide nanoribbons with edge functionalization

Edge-functionalization is an important method for the band engineering of nanoribbons (NRs). Implementing the first principle calculations, we investigate the electronic band structure of zigzag-edge alpha-carbon phosphide NRs with different edge functionalization. It was found that the NRs are semiconductors with their double edges passivated by H, OH, F or Cl. However, the NR exhibits metallic behavior when the two edges bind to oxygen. Furthermore, as one of the edges is oxidized, regardless of the other edge with H, OH, F, or Cl passivation, the NRs can show unique metallic properties. The H, F and Cl passivation can break the spin degeneracy in the ferromagnetic state and a fully polarized phenomenon can be observed in specific energy ranges. In addition, in combination with the nonequilibrium Green's function, we study the transport properties of the designed devices. We found that the device with an edge passivated by O and H exhibits a low-bias negative differential resistance effect with an ultrahigh peak-to-valley ratio, which demonstrates their potential application in sensitive devices. In particular, the perfect Seebeck effect has also been observed when the temperature could be taken as the source and drain leads. Our results indicate that edge-functionalization greatly expands the application of alpha-carbon phosphide NRs.