Strain tailored electronic and optical properties of AEMTe compounds

Abstract

The need to develop high-performance optoelectronic and semiconductor materials drives the search for new materials with tunable electronic and optical properties. The alkaline earth metal tellurides (AEMTe, where AEM = Be, Mg, Ca, Sr, and Ba) are particularly appealing among the group II–VI binary semiconductors because of their unique electrical structures and potential for band gap engineering. This study employs a thorough DFT-based methodology to examine the structural and optical characteristics of these structures. To guarantee high-fidelity findings, we combined scalar-relativistic ONCV pseudopotentials with RRKJ ultrasoft in the PBE-GGA framework. The core of our analysis centers on how the material shifts under strain; specifically, we evaluated electronic band structures at −5%, 0%, and +5% strains. This allowed us to determine exactly how compressive and tensile forces modify the compounds' fundamental characteristics. Phonon dispersion calculations confirm the dynamical stability of the cubic phases of BeTe, CaTe, SrTe, and BaTe, but suggest structural instability of the cubic Zinc Blende phase of MgTe. Notably, the band gap pressure coefficients are found to be anomalous, with most compounds showing negative pressure coefficients except for MgTe, which shows a strong positive pressure coefficient due to its dynamical unstable character. The exhaustive computational results demonstrate that the dynamical stable members of the AEMTe series offer very responsive and tunable electronic and dielectric environments. The strict qualitative trends offer strong evidence that epitaxial strain engineering might find successful applications to systematically tune absorption thresholds, dielectric screening and static refractive indices. Therefore, these strained alkaline earth metal tellurides are found to be very promising foundational candidates for future theoretical explorations and experimental integrations in advanced optoelectronics and strain-sensitive sensory architectures.