Insight into physical properties of carbon-doped BeSiP2 and BeGeP2 chalcopyrite: An ab initio study.

Our present article reports the carbon substitution-driven changes in the behavior of BeSi 1- x C x P 2 and BeGe 1- x C x P 2 (x = 0.25 and 0.5) chalcopyrite alloys using the full-potential augmented plane wave plus local orbital (FP-APW + lo) based first-principles calculations. The lattice constants (a and c) of BeSi 1- x C x P 2 and BeGe 1- x C x P 2 are shortened, and the bulk moduli are improved as carbon atoms replace Si and Ge atoms. The computed negative formation energy (E f) indicate adequate thermodynamic stability of the BeSi 1- x C x P 2 and BeGe 1- x C x P 2 alloys. The bandgaps pristine BeSiP 2 and BeGeP 2 computed as 1.84 eV and 1.54 eV, respectively, using the modified Tran-Blaha (TB) Becke Johnson (mBJ) transition potential, matching well to the experimental results. However, the C substitution is found to narrow the bandgap of BeSiP 2 and BeGeP 2 considerably. Similarly, C substitution is found to reduce electrons' and holes' effective mass and enhance the absorption coefficient of BeSi 1- x C x P 2 and BeGe 1- x C x P 2 alloys up to (α ∼ 10 5 c m − 1 ). Our predictions indicate that the physical properties of BeSiP 2 and BeGeP 2 chalcopyrite can be modified effectively by replacing C in the Si and Ge sites, which makes them promising for optoelectronic applications. Lattice parameters and bulk modulus versus C concentration of BeSiP 2 and BeGeP 2. [Display omitted] • Some physical properties of C doped BeSiP 2 and BeGeP 2 chalcopyrite are investigated. • The calculated electronic and optical properties of pure BeSiP 2 and BeGeP 2 compare well with the available data. • The substitution of carbon decreases the value of bandgaps, hole and electron masses. • Doping BeSiP 2 and BeGeP 2 enhance the absorption in visible light making them promising for optoelectronic applications. [ABSTRACT FROM AUTHOR]