Significant NDR and perfect spin-filtering effect based on phosphorus doped sawtooth penta-SiC 2 nanoribbon: A first-principles study

We investigate the site dependent effects of substitutional phosphorus doping on the geometric structure, electronic properties, magnetic properties, and transport characteristics of penta-SiC₂ nanoribbons using the density functional theory (DFT) combined with non-equilibrium Green's functions (NEGF). Phosphorus doping can introduce atomic spin polarization and usually results in an antiferromagnetic (AFM) ground state at C sites, where the spin polarizations in any two neighbor primitive cells are oppositely orientated. Nevertheless, the energetic difference between the AFM and ferromagnetic (FM) states are small and most of the systems should become quasi-paramagnetic at room temperature. In this case, negative differential resistance (NDR) behavior may appear and an exceptionally high peak-to-valley current ratio (PVR) of up to 9.57 × 10⁷ is predicted in doping configuration P@C6. The FM states can be the ground states with doping at one Si site and nearly perfect spin filtering might be achieved at low temperature in configurations P@Si3. This study highlights the profound influence of doping on the physical properties of SiC2-based nanostructures and offers theoretical guidance for the design of spintronic devices and high-speed electronic switches based on SiC₂ nanoribbons.