Impact of stacking sequence on the tight-binding electronic band structures of (BeX)m/(ZnX)m, X = S, Se and Te superlattices

Abstract

By using a semi-empirical tight-binding sp3s* method, the results of comprehensive electronic band structures are reported for the zinc-blende beryllium- and zinc-chalcogenides (BeX and ZnX; X = S, Se, Te) as well as their representative (BeX)m/(ZnX)m (001) superlattices (SLs). For the bulk BeX and ZnX materials, the simulations of energy band dispersions Ejk→ have offered the correct band gaps in very good agreement with the first-principles calculations. The band-mixing effect through the interfaces of two constituent compounds (BeX indirect- and ZnX direct-band gap) has played an important role for determining the overall band lineup in the (BeX)m /(ZnX)m SLs over the entire Brillouin zone. Based on the quantum confinement effects, the impact of stacking sequence m ≤ 10 is carefully examined for assessing the band structures of SLs. The results have clearly revealed that the nature of energy bandgaps is quite sensitive to the choice of well (BeX) and barrier (ZnX) layer thickness. Obviously, this intuition has implied that controlling m to achieve direct bandgaps in novel (BeX)m/(ZnX)m SLs is probably an effective way of assessing their potential use in technologically important optoelectronic devices.