Electronic structure of (111) and (211) strained-layer superlattices

The electronic structure of strained-layer superlattices has been subject t o increasing attention. This is due to high-quality samples that can be gro wn from layers with a lattice mismatch of up to 7 % if the constituent slab s of the strained materials are kept sufficiently thin. Apart from the stan dard effects of band offset and slab thickness, the electronic structure of these superlattices is also affected by the strains involved. The electron ic properties can also exhibit an important dependence on the growth direct ion, which results in different planar projections of the conduction and th e valence bands of the constituent crystals. Until now, the best-studied ca se, from both experimental and theoretical points of view, are the (001)sup erlattices. However, less attention has been paid to quantum wells and supe rlattices grown along high-index directions [N11]. We study the electronic properties of (111) and (211) strained-layer superlattices by using an sp(3 )s* empirical tight-binding model together with the surface Green-function watching method.