Theoretical study of band-edge states in Sn1Gen strained-layer superlattices.

Abstract

Recently, ${\mathrm{Sn}}_{1}$${\mathrm{Ge}}_{\mathit{n}}$ (ng10) strained-layer superlattices grown along the [001] direction have been fabricated in spite of the large lattice mismatch (13%) between the two constituents. Sn/Ge superlattices, with a small positive band gap, could have applications in far-infrared optoelectronics. In this paper, we present a detailed study of spin splittings in ${\mathrm{Sn}}_{1}$${\mathrm{Ge}}_{\mathit{n}}$ strained-layer superlattices without inversion symmetry. The effective masses for the ${\mathrm{Sn}}_{1}$${\mathrm{Ge}}_{3}$ structures have also been calculated. These band-edge properties are correlated with the nature of the superlattice states in both real space and wave-vector space and are compared with those of GaAs/AlAs and Si/Ge superlattices. Our calculations are based on the linear-muffin-tin-orbital and the empirical tight-binding methods.