Electronic and mechanical properties of monocrystalline silicon doped with trace content of N or P: A first-principles study

Monocrystalline silicon is highly promising for applications as semiconductor materials in electronic devices. However, the intrinsic brittleness of Si as well as the relatively low conductivity has restricted its wide application. In this paper, the optimized electronic and mechanical properties of monocrystalline silicon doped with trace content of N or P (SiMx, X = 0, 0.2%, 0.46%, 1.5%, M = N, P) were investigated by first-principles calculations. The results show that the doping of N or P elements can improve the mechanical and electronic properties of monocrystalline silicon, and with the increase of doping concentration, the improving effect becomes more obvious. In addition, the doping of N has a stronger effect on Si than that of P. The doping N, P atoms can form polar covalent bonds to enhance the covalency between atoms, improve the mechanical of Si. Electronic structure analysis shows that the doping of N or P atom makes the hybridization of s-orbital and p-orbital stronger, thus narrows the band gap and improves the conductivity of Si. Furthermore, as the concentration of doping elements increases, Si goes from indirect to direct semiconductor, which is beneficial to improve the recombination of excited electron-hole pairs due to there is no momentum difference between the two positions in k space.