First-principles calculations to investigate structural, electronic and optical properties of (BeTe)n/(CdS)n superlattices

• Special attention has to be paid to the BeTe/CdS compounds, because the two binary which are involved have no common atoms.
• The relevance of the BeTe/CdS is in combination of different band gap type and combination of different direct band values.
• It is found that CdS and (BeTe)n/(CdS)n superlattices exhibit a direct fundamental band gap.
• The direct gap character that the (BeTe)n/(CdS)n superlattices exhibit is of great importance for the optical transitions.
• The (BeTe)n/(CdS)n (SLs) materials might be useful for the design of quantum well lasers and solar cell heterostructures.

Structural, electronic and optical properties of binary BeTe and CdS compounds and their (BeTe)n/(CdS)n superlattices (SLs) are investigated using the first-principles full potential linear muffin-tin orbitals method (FP-LMTO). The exchange–correlation potential is treated with the local density approximation of Perdew and Wang (LDA-PW). The ground-state properties are determined for the bulk materials (BeTe, CdS, and (BeTe)n/(CdS)n) in cubic phase. The calculated structural properties of BeTe and CdS compounds are in good agreement with available experimental and theoretical data. It is found that BeTe exhibit an indirect fundamental band gap and CdS and their superlattices (SLs) exhibit a direct fundamental band gap, which might make (BeTe)n/(CdS)n superlattices (SLs) materials promising and useful for optoelectronic applications. The fundamental band gap decreases with increasing the number of monolayer n.