Dielectric function of (ZnxCd1-x)3P2 alloy system in the region of direct optical transitions

TL;DR

This paper investigates the dielectric function of the (ZnxCd1-x)3P2 alloy system using theoretical models, analyzing how optical properties vary with composition and polarization, especially near direct band transitions.

Contribution

It provides a detailed theoretical analysis of the dielectric function in (ZnxCd1-x)3P2 alloys considering polarization and composition effects, which was not previously explored.

Findings

Dielectric function peaks near the band gap energy region.

Imaginary part of dielectric function reaches a plateau at high energies.

Longitudinal dielectric function is consistently less than transverse for all compositions.

Abstract

The band structure of (ZnxCd1-x)3P2 alloy system is considered within the framework of Kildal's band model. Frequency dependencies of real and imaginary parts of dielectric function were received and analyzed in terms of direct band to band transitions. Theoretical calculations were performed for light polarized both parallel and perpendicular to the c- axis of the crystal. In calculations the selection rules for optical transitions were applied. The frequency dependence of real part of dielectric function is described by a maximum in hv=(1,2 - 1,5)Eg energy region. In high energy region hv>>Eg the imaginary part of dielectric function has a plateau. Longitudinal dielectric function is less than the transverse dielectric function for all compositions x of (ZnxCd1-x)3P2 alloy system both for real and imaginary parts. When turning from Zn3P2 to Cd3P2 the reduction of dielectric function values occurs.