Characteristics of Si δ-layers embedded in GaAs

An ultrathin, 1-6 monolayers (MLs) thick, Si delta-layer, is embedded in bulk GaAs. The normally observed self-assembling with resulting phase separation can be avoided up to delta-layer thicknesses of 4MLs, which opens the possibility to study two-dimensional (2D) properties of this III-V/IV heterostructure. Optical, electrical, transport and structural characterization of the Si delta-layer has been carried out. In luminescence, two novel emission bands are observed, which are blue-shifted as the width of the Si delta-layer is reduced, indicating pronounced 2D properties. The derived results on transition energies and electronic structure are compared with theoretical predictions obtained by a self-consistent approach.