The structural, electronic and optical response of IIA–VIA compounds

What is it about?

The structural, electronic and optical properties of IIA–VIA compounds are performed, by using the full-potential linearized augmented plan wave (FP-LAPW) method within DFT, by using the (PBEsol-GGA 2008) version. We have compared the modified Becke–Johnson (mBJ) potential to LDA, GGA and EV-GGA approximations. The IIA–VIA compounds have rock salt structure (B1) and zinc-blend structure (B3). The results obtained for band structure using mBJ show a significant improvement over previous theoretical work and give closer values to the experimental results. The bandgaps less than 3.1 eV are used in the visible light devices applications, while those with bandgaps bigger than 3.1 eV, used in UV devices applications. Optical parameters, like the dielectric constant, refractive indices, reflectivity, optical conductivity and absorption coefficient are calculated and analyzed. Refractive index lesser than unity (vg=c/n) shows that the group velocity of the incident radiation is greater than the speed of light.

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Why is it important?

The IIA–VIA chalcogenides are technically very important having applications ranging from catalysis to microelectronics. These compounds are used in the region of luminescent devices [3]. The IIA–VIA chalcogenides have potential applications in light emitting diodes and laser diodes. After the investigation of the structural phase transition, metallization, cohesive and elastic properties under high pressure, IIA–VIA chalcogenides achieved great importance during last twenty years. The study of these compounds under high pressure persuaded the interest with the targeted physical properties. Due to unusual properties and wide band gap under high pressure these compounds have greatly attracted the research community. The IIA–VIA chalcogenides have no “d” electron in their valance band, which is an important feature in the research field. The compressed behavior and the metallization phenomena study have become possible due to the static pressure techniques.

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