Table 1
Input parameters: number of plane waves, energy cut-off and muffin-tin radii.
| Compounds | NPLW (Total) | Ecut [Ryd] | MTS [a.u.] | ||||
|---|---|---|---|---|---|---|---|
| Be | Te | Zn | Se | ||||
| (BeTe)1/(ZnSe)1 | 16242 | 137.1748 | 2.122 | 2.476 | 2.122 | 2.476 | |
| (BeTe)2/(ZnSe)2 | 32458 | 137.0922 | 2.024 | 2.526 | 2.165 | 2.392 | |
| (BeTe)3/(ZnSe)3 | 48690 | 137.6625 | 2.020 | 2.540 | 2.158 | 2.401 | |
| (BeTe)1/(ZnSe)3 | 32458 | 137.0651 | 2.123 | 2.477 | 2.180 | 2.392 | |
| (BeTe)3/(ZnSe)1 | 32458 | 137.3635 | 2.022 | 2.540 | 2.121 | 2.474 | |
| (BeTe)2/(ZnSe)4 | 48690 | 137.3247 | 2.022 | 2.528 | 2.172 | 2.401 | |
| (BeTe)4/(ZnSe)2 | 48690 | 137.6141 | 2.020 | 2.546 | 2.140 | 2.431 | |
| (BeTe)1/(ZnSe)5 | 48690 | 137.0638 | 2.123 | 2.477 | 2.182 | 2.401 | |
| (BeTe)5/(ZnSe)1 | 48690 | 138.0711 | 2.017 | 2.548 | 2.108 | 2.475 | |
Table 2
Calculated lattice parameter a ( Å), bulk modulus B0 (GPa), derived modulus B′0 and gap energy Eg(eV) for the binary compounds at equilibrium volume.
| Lattice constant (Å) | Bulk modulus B0 (GPa) | Eg(eV) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| This work | Exp | Other works | This work | Exp | Other works | This work | Exp | Other works | This work | Exp (Γ-X) | Other works |
| BeTe 5.588 | 5.617A | 5.581B, 5.58C | 56.448 | 66.8A | 62.36B, 60C, 71D, 55E, 71F, 64.90G | 3.62 | 4A | 3.69B, 3.72C | 1.907 | 2.7H | 1.76G, 1.8D |
| 5.53D, 5.556E | 71D, 55E | 3.38D, 3.56E | |||||||||
| 5.531F, 5.556G | 71F, 64.90G | 3.377F, 3.40G | |||||||||
| Exp (Γ-Γ) | |||||||||||
| ZnSe 5.65 | 5.667I, J | 5.624K,5.618L, 5.666M | 59.68 | 64.7I | 71.82K, 67.6L | 3.96 | 4.77I | 4.88K, 4.67L | 1.0963 | 2.82Q | 1.31K |
| 5.666n | 67.32M, 62.45n | 4.05n, 599O | 1.863R | ||||||||
| 5.578O, 5.611P | 71.84O, 75.20P | 4.57P | 1.83S | ||||||||
A a[13],
B b[14],
C c[15],
A a[13],
B b[14],
C c[15],
D d[16],
E e[17],
F f[18],
G g[19],
A a[13],
B b[14],
C c[15],
H h[20],
G g[19],
D d[16],
D d[16],
E e[17],
D d[16],
E e[17],
D d[16],
E e[17],
F f[18],
G g[19],
F f[18],
G g[19],
F f[18],
G g[19],
I i[21],
J j[22],
K k[23],
L l[24],
M m[25],
I i[21],
K k[23],
L l[24],
I i[21],
K k[23],
L l[24],
Q q[29],
K k[23],
M m[25],
O o[27],
R r[30],
O o[27],
P p[28],
O o[27],
P p[28],
P p[28],
S s[31].
Table 3
The calculated equilibrium constant a ( Å), bulk modulus B0 (GPa) and B′0 for superlattices (BeTe)n/(ZnSe)m.
| Compounds | a(Å ) | B0 (GPa) | |
|---|---|---|---|
| (BeTe)1/(ZnSe)1 | 5.619 | 58.947 | 4.99803 |
| (BeTe)2/(ZnSe)2 | 11.241 | 59.829 | 4.14331 |
| (BeTe)3/(ZnSe)3 | 16.826 | 62.328 | 4.16186 |
| (BeTe)1/(ZnSe)3 | 11.242 | 64.827 | 4.93767 |
| (BeTe)3/(ZnSe)1 | 11.230 | 60.270 | 3.47019 |
| (BeTe)2/(ZnSe)4 | 16.847 | 64.97 | 4.38255 |
| (BeTe)4/(ZnSe)2 | 16.830 | 61.299 | 3.17126 |
| (BeTe)1/(ZnSe)5 | 16.863 | 65.856 | 4.64635 |
| (BeTe)5/(ZnSe)1 | 16.802 | 58.065 | 3.36946 |
Table 4
Calculated energy band gaps.
| Compounds | Eg (eV) | Nature |
|---|---|---|
| (BeTe)1/(ZnSe)1 | 1.829038 | Gap direct |
| (BeTe)2/(ZnSe)2 | 2.102459 | Gap direct |
| (BeTe)3/(ZnSe)3 | 1.933643 | Gap direct |
| (BeTe)1/(ZnSe)3 | 1.582407 | Gap direct |
| (BeTe)3/(ZnSe)1 | 1.858339 | Gap indirect |
| (BeTe)2/(ZnSe)4 | 1.706723 | Gap direct |
| (BeTe)4/(ZnSe)2 | 1.971915 | Gap direct |
| (BeTe)1/(ZnSe)5 | 1.427891 | Gap direct |
| (BeTe)5/(ZnSe)1 | 1.852561 | Gap indirect |
Fig. 1
Band structure along the symmetry lines of the Brillouin zone for (BeTe)n/(ZnSe)m superlattices at direct band gap.
Fig. 2
Band structure along the symmetry lines of the Brillouin zone for (BeTe)n/(ZnSe)m superlattices at indirect band gap.
Fig. 3
Total and partial density of states (DOS) for BeTe and ZnSe compounds.
Fig. 4
Total and partial density of states (DOS) for (BeTe)n/(ZnSe)msuperlattices with n = m = 1, 3 and n ≠ m (1, 3).
Fig. 5
Calculated dielectric functions (real and imaginary) for (BeTe)n/(ZnSe)n superlattices at direct band gap.
Fig. 6
Calculated refractive index n(w) for (BeTe)n/(ZnSe)n superlattices at direct band gap.
Fig. 7
Calculated reflectivity R(w) for (BeTe)n/(ZnSe)n superlattices at direct band gap.