First principles calculations of electronic and optical properties of GaN_1−xBi_x alloys

The electronic and optical properties of the ternary GaN_1−xBi_x alloys in the zinc-blende structure are theoretically investigated by first principles calculations. Geometric optimization is performed before all the simulations to get accurate results. The band gaps of the alloys are found to be direct even with x = 6.25%, and would become smaller when increasing the Bi compositions. The decrease ratio of band gaps is approximately 227 meV when 1% of N is replaced by Bi in the range of x = 0–6.25%. Meanwhile, the absorption coefficient is shown to be significantly changed induced by the incorporation of Bi. These interesting properties indicate that GaN_1−xBi_x alloys could be a promising candidate in future optoelectronic applications. (semiconductor physics)