A method of forming an optically active region on a silicon substrate includes the steps of epitaxially growing a silicon buffer layer on the silicon substrate and epitaxially growing a SiGe cladding layer having a plurality of arrays of quantum dots disposed therein, the quantum dots being formed from a compound semiconductor material having a lattice mismatch with the silicon buffer layer. The optically active region may be incorporated into devices such as light emitting diodes, laser diodes, and photodetectors.