Elastically strained GeSiSn layers and GeSiSn islands in multilayered periodical structures

This work deals with elastically strained GeSiSn films and GeSiSn islands. The kinetic diagram of GeSiSn growth for different lattice mismatches between GeSiSn and Si has been drawn. The multilayered periodic structures with pseudomorphic GeSiSn layers and GeSiSn island arrays have been obtained. The density of the islands in the GeSiSn layer is 1.8 · 1012 cm-2 for an average island size of 4 nm. Analysis of the rocking curves has shown that the structures contain smooth heterointerfaces, and no abrupt changes of composition and thickness between periods have been found. Photoluminescence has been demonstrated and calculation of band diagram with the model-solid theory has been carried out. Luminescence presented for sample with pseudomorphic Ge0.315Si0.65Sn0.035 layers in the narrow range 0.71–0.82 eV is observed with the maximum intensity near 0.78 eV corresponding to 1.59 µm wavelength. Based on the band diagram calculation for Si/Ge0.315Si0.65Sn0.035/Si heterocomposition we have concluded that 0.78 eV photon energy luminescence corresponds to interband transitions between the X-valley in Si and the heavy hole subband in the Ge0.315Si0.65Sn0.035 layer