Effect of tensile-strained Si layer on photoluminescence of Ge(Si) self-assembled islands grown on relaxed SiGe/Si(001) buffer layers

The results of studying the photoluminescence of the structures with Ge(Si) self-assembled islands embedded into tensile-strained Si layer are reported. The structures were grown on smooth relaxed Si_{1 ? x} Ge_x/Si(001) (x = 0.2–0.3) buffer layers. The photoluminescence peak found in the photoluminescence spectra of the studied structures is related to the indirect (in real space) optical transition between the holes localized in the Ge(Si) islands and electrons localized in the tensile-strained Si layers under and above an island. It is shown that one can efficiently control the position of the photoluminescence peak for a specified type of structure by varying the thickness of the strained Si layers. It is found that, at 77 K, the intensity of the photoluminescence signal from the heterostructures with Ge(Si) self-assembled islands contained between the tensile-strained Si layers exceeds by an order of magnitude the intensity of the photoluminescence signal from the GeSi structures with islands formed on the Si(001) substrates.