Strain-induced composition-dependent phonon and thermodynamical characteristics of BeZnX chalcogenide alloys and BeX/ZnX superlattices
Department of Physics, University of North Florida, 1 UNF Drive, 32224-7699, Jacksonville, FL, USA
2 Department of Physics, Indiana University of Pennsylvania, 975 Oakland Avenue, 56 Weyandt Hall, 15705-1087, Indiana, PA, USA
Accepted: 6 December 2022
Published online: 21 December 2022
The results of a comprehensive lattice dynamical study are reported by using a realistic rigid ion model (RIM) for the novel zinc-blende binary (BeX, ZnX) compounds, ternary (BexZn1−xX) alloys and short-period (BeX)n/(ZnX)n superlattices (SLs), with X = Se, Te. In the RIM, we have meticulously included as well as accurately appraised the short-range forces up to second nearest neighbors and long-range Coulomb interactions for all the binary, ternary materials, and superlattice structures. Distinct variations perceived in the simulated phonon frequencies and thermodynamical traits of BeX, ZnX compounds including the ideal BexZn1−xX ternary alloys are attributed to the differences between cation (Be, Zn) and anion (X) masses as well as changes in their bond lengths, bond strength and bond (Be-X, Zn-X) covalency. In the short-period (BeX)n/(ZnX)n (001) SLs (n ≤ 4), the phonons propagating normally and obliquely to the interfaces as well as the anisotropy of zone-center modes are carefully examined while identifying the confined optical-, quasi-confined optical and interface phonons. The simulated results of phonon features are compared/contrasted very well with the existing experimental and theoretical data. Controlling the vibrational traits by altering the number of BeX, ZnX monolayers (n, m) in (BeX)n/(ZnX)m SLs can provide excellent opportunities of improving their electrical and thermal properties for engineering various electronic device structures.
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