The electronic band structure of Ge1−xSnx in the full composition range: indirect, direct, and inverted gaps regimes, band offsets, and the Burstein-Moss effect

A comprehensive and detailed study of the composition dependence of lattice constants, band gaps and band offsets has been performed for bulk Ge1−xSnx alloy in the full composition range using state-of-the-art density functional theory methods. A spectral weight approach to band unfolding has been applied as a means of distinguishing the indirect and direct band gaps from folded supercell band structures. In this way, four characteristic regions of the band gap character have been identified for Ge1−xSnx alloy: an indirect band gap (x