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

Abstract

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.