Tuning the structural and optical properties of GeSiSn/Si multiple quantum wells and GeSn nanostructures using annealing and a faceted surface as a substrate

[Display omitted] •PL mechanisms in the GeSiSn/Si MQW structure were studied after annealing.•A several-fold increase in PL was observed in the GeSiSn/Si MQW with a faceted surface.•The growth conditions of GeSn cross-structures on an MQW surface were established.•The PL enhancement in the system of plasmonic cross-structures/MQWs was revealed.•The GeSn nanoislands appearing on a faceted surface demonstrated their interband PL. The optical properties of GeSiSn/Si multiple quantum wells (MQWs) and GeSn nanostructures are studied in the range of 1.3–4 µm. An annealing at the temperature of 650 °C leads to the concentration decrease of vacancy complexes and the intensity increase of the radiative recombination proceeding through the interband luminescence. The energy diagram calculation showed that the transitions occur between the heavy hole subband of the GeSiSn solid solution and the silicon X-valley. A several-fold increase in the photoluminescence was observed in structures containing a nanostructured faceted surface with a (113) facet in the lower part of the MQW structure. The analysis of the reciprocal space map of such structures indicates the bending of the (001) flat growth front during the layer deposition at the faceted pit edges within the (113) facet. The GeSn cross-structure and nanoisland array were first obtained using the nanostructured faceted surface on top of the MQW structure. The regularities of the GeSn nanostructure formation on the deposition rate, the layer thickness, as well as the growth temperature, were investigated. The cross-structures on top of the GeSiSn/Si MQW structure are considered promising as plasmonic nanoantennas amplifying the signal from the multilayer periodic structures.