First principle calculations of structural, elastic, electronic and optical properties of cubic Cd1-x-yZnxHgyTe triangular quaternary alloys and their compounds

Abstract

Structural, elastic, electronic and optical properties of zinc blende Cd1-x-yZnxHgyTe quaternary alloys and their allied compounds are calculated with DFT based FP-LAPW approach. Structural and mechanical properties are computed with PBE-GGA potentials, while mBJ-GGA and GGA + U potentials are employed to compute electronic and optical properties. All the thermodynamically stable specimens show mechanical stability, elastic anisotropy, ductility, mixed type of bonding etc. Each alloy shows direct (Γ-Γ) band gap (Eg) with EgmBJ−GGA>EgGGA+U. Electrons play dominant role over holes in carrier transportation. Exclusive or collective effort of the Te-5p→Zn-5s, Cd-6s, Hg-7s electronic transitions contribute peaks in the ε2(ω) spectra of any specimen. Specimen with higher band gap possesses lower zero-frequency limits, but requires higher critical point energies in different optical spectra and vice versa. Calculated oscillator strength of quaternary alloys show presence of sufficient number of electrons in unoccupied conduction states beyond 27.0 eV during optical excitations.