OPTICAL-PROPERTIES OF SI-GE SUPERLATTICES

All existing models of the electronic and optical properties of Si-Ge heterostructures are based on an idealised, infinite superlattice model with abrupt interfaces. In this study we adopt a computational model which makes it possible to go beyond such idealisations. This is achieved without having to truncate the microscopic account of the crystal potential. We assess the effect of the finite character of heterostructures, and of the breakdown of the translational symmetry in the interface plane due to interdiffusion and defects, on electronic structure and optical properties. In particular, we establish a link between the interface quality and the shape of infrared spectra. We also evaluate the key electronic and optical properties of related systems, e.g. Si-SixSn1-x and Ge-Ge x Sn1-x . © 1990 AIME.