S. Botti et Lc. Andreani, Electronic states and optical properties of GaAs/AlAs and GaAs/vacuum superlattices by the linear combination of bulk bands method - art. no. 235313, PHYS REV B, 6323(23), 2001, pp. 5313
The linear combination of bulk bands method recently introduced by Wang, Fr
anceschetti, and Zunger [Phys. Rev. Lett. 78, 2819 (1997)] is applied to a
calculation of energy bands and optical constants of (GaAs)(n)/(AlAs)(n) an
d (GaAs)(n)/(vacuum)(n) (001) superlattices with n ranging from 4 to 20. Em
pirical pseudopotentials are used for the calculation of the bulk energy ba
nds. Quantum-confinement induced shifts of critical point energies are calc
ulated and are found to be larger for the GaAs/vacuum system. The E-1 peak
in the absorption spectra has a blueshift and splits into two peaks for dec
reasing superlattice period; the E-2 transition instead is found to be spli
t for large-period GaAs/AlAs superlattices. The band contribution to linear
birefringence of GaAs/AlAs superlattices is calculated and compared with r
ecent experimental results of Sirenko et al. [Phys. Rev. B 60, 8253 (1999)]
. The frequency-dependent part reproduces the observed increase with decrea
sing superlattice period, while the calculated zero-frequency birefringence
does not account for the experimental results and points to the importance
of local-field effects.