Intense Photoluminescence from Ge(Si) Self-Assembled Islands Embedded in a Tensile-Strained Si Layer

The interest in the Ge/Si heterostructures with self-assembled islands is associated with their potential use for Si-based optoelectronic devices. Due to the effective hole 3D confinement a photoluminescence (PL) signal from Ge(Si) islands was observed up to room temperature. However, only holes are effectively localized in Ge(Si) islands, while electrons are only weakly confined in Si on the heterojunction with an island. A weak confinement of electrons is one possible reason for the rather low PL intensity from islands. It is known that the tensile-strained Si layer (e-Si layer) grown on relaxed SiGe buffer is an effective potential well for the electrons. The embedding of Ge(Si) islands in such a e-Si layer will essentially improve the localization of electrons on the heterojunction with an island which can result in the increase of PL signal from islands. In this paper we report on photoluminescence study of structures with Ge(Si) islands embedding between e-Si layer