Photoluminescence of annealed Al₂O₃/Ge and Al₂O₃/Si/Ge/Si multilayer nanostructures

We perform a photoluminescence comparison of Ge nanocrystals in an Al₂O₃ matrix structures with similar Ge-Si core–shell nanoparticles structures. Al₂O₃/Ge and Al₂O₃/Si/Ge/Si nanoperiodic structures were obtained by electron beam evaporation with subsequent high-temperature (800–900 °C) annealing in an inert medium. The first type of structure has an intensive visible luminescence, which may be associated with a large number of structural defects. Al₂O₃/Si/Ge/Si structures have a very weak photoluminescence in the visible spectral region and an additional maximum in the 800–1000 nm. The last one is caused mostly by Ge/SiGe nanocrystals. Further work to enhance this infrared emission by increasing the layer thickness, testing annealing modes, duration, and annealing atmosphere opens up prospects for the use of such structures in light-emitting devices.