The optical—electrical properties of doped β-FeSi₂

By using the pseudo-potential plane-wave method of first principles based on the density function theory, the geometrical, electronic structures and optical properties of FeSi_1.875M_0.125 (M = B, N, Al, P) were calculated and analyzed. The calculated structural parameters depend strongly on the kinds of dopants and sites. The total energy calculations for substitution of dopants at the SiI and the SiII sites revealed that Al and P prefer the SiI sites, whereas B and N prefer the SiII sites. The calculations predict that B- and Al-doped β-FeSi₂ show p-type conduction, while N- and P-doped show n-type. Optical property calculations show that N-doping has little influence on the complex dielectric function of β-FeSi₂; B-, N-, Al- and P-doping can enhance the electronic transition, refractive index, and reflection effect in the low-energy range, and weaken the reflection effect at the max peak of reflectivity. These results can offer theoretical guidance for the design and application of optoelectronic material β-FeSi₂.