Ab initio study of structural and electronic properties of (GaN)n/(AlN)n superlattices

Structural and electronic properties of binary GaN and AlN compounds and their superlattices (SLs) (GaN)(n)/(AlN)(n) 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 GaN, AlN, and their superlattices (GaN)(n)/(AlN)(n)) in cubic phase. The calculated structural properties of GaN and AlN compounds are in good agreement with available experimental and theoretical data. It is found that AlN exhibit an indirect fundamental band gap while that GaN and the superlattices (SLs) exhibit a direct fundamental band gap, which might make the superlattices (GaN)(n)/(AlN) n materials promising and useful for optoelectronic applications. The fundamental band gap decreases with increasing the number of monolayer.