Effect of Single Atom Doping on Structural, Electronic and Magnetic Properties of Hexagonal Silicon Carbide (4H-SiC) for Spintronic Application: A first principle study

Abstract

In this paper, the structural geometry, electronic and magnetic properties of single magnesium (Mg) and vanadium (V) atoms doped 4H- SiC system were investigated. For the structural geometry of each sample, the energy substitution, as well as bond length, were  calculated; results obtained indicate that the bond length of Silicon-Magnesium (Si-Mg) and SiliconVanadium (Si-V) was 1.90 Å and 2.02 Å  respectively, greater than that of silicon-carbon (SiC) 1.89 Å in pure SiC. This result indicates that the bond length increases due to the introduction of dopants with greater radii than that of Si. It also shows that both Mg and V doping changes the structure from non- magnetic ordering to magnetic in nature. The band structure result for both undoped and doped shows the presence of valence band  maximum (VBM) and conduction band minimum (CBM) around different symmetry points which indicate an indirect band gap nature.  The calculated band gap of pure 4H SiC is found to be ~ 2.21 eV, which is at a wide band gap material range, but with the introduction of  Mg and V dopants, the band gap reduced significantly to ~0.4 eV and ~0.45 eV respectively. The density of state (DOS) and projected  density of state (PDOS) show the contributions of the various states in both the VBM and CBM; after doping the Fermi energy is shifted  towards higher energy and enters into the conduction band, exhibiting spin polarization. Both DOS and PDOS indicated that the  magnetic moments mainly come from the 2p orbitals of Si atoms and 3p for Mg dopant and 3d orbitals for V dopant. The magnetic  moment for 4H-SiC/Mg and 4H-SiC/V was calculated to be 2.23 μB and 3.24 μB.