Structural and optoelectronic properties of Zn1-x-yBexMgyTe/InP quaternary alloys: A theoretical study

Density functional calculations show that designed zinc blende Zn1-x-yBexMgyTe/InP quaternary alloys are Γ-centered direct band-gap semiconductors and stable within a wide compositional range. Enhancement in the of Be and Mg compositions sum enhances lattice constant, but reduces minimum band-gap of these quaternary alloys. The Te-5p of valence to Zn-5s; Be-2p,3s; Mg-4s, 3p of conduction band HOMO-LUMO electronic excitations collectively control their optical properties. Such transitions show significant optical absorption in the ultra-violet (UV) region of the electromagnetic spectrum. Calculated optical energy-gaps of these alloys reside in the UV region. Optical energy-gap of quaternary alloy is found to be overestimated with respect to the corresponding fundamental band-gap. With enhancement in the Be and Mg compositions sum, both the fundamental band-gap and optical energy-gap exhibit blue-shift. Computed ε1 (0), n (0) and R (0) reduces with growing band-gap and vice versa. These Zn1-x-yBexMgyTe/InP semiconductor quaternary alloys with such optoelectronic features would be compatible for fabricating UV optoelectronic devices

Cationic and anionic composition-dependent mechanical and thermal properties of zinc-blende specimens under

Elastic and thermal properties of zinc-blende $${\hbox {Mg}}_{x} {\hbox {Zn}}_{1\hbox {-}x} {\hbox {S}}_{y} {\hbox {Se}}_{1\hbox {-}y}$$ quaternary alloys and their constituent binary/ternary compounds have been computed through first principles calculations. Elastic stiffness constants of specimens have been increased almost linearly with increasing sulfur composition at any fixed magnesium composition, while reverse trends have been observed with increasing magnesium composition at any fixed sulfur composition in each binary–ternary/ternary–quaternary system. Hardness of specimens has been increased almost linearly with increasing sulfur composition at any fixed magnesium composition, while it has been decreased with increasing magnesium composition at any fixed sulfur composition in each system. Mechanical stability, elastic anisotropy, compressibility, ductility and plasticity have been observed in each compound. Mixture of covalent and ionic bonding with prominent role of covalent nature, dominating role of bond bending over stretching and central nature of interatomic forces have been investigated in each compound. Interaction between the atoms in any compound has been observed to be anharmonic in nature via calculated Gruneisen parameter. Computed Debye temperature, Debye frequency, thermal conductivity and melting temperature of all the specimens have also been reported