Nanostructures formed by sub- and close-to-critical Ge inclusions in a Si matrix

We report on the defect-free (i) nanostructures formation by sub-critical (less than 1 monolayer) inclusions of Ge in a Si matrix and appearance of the new photoluminescence lines from the multilayer structures correlated with the formation of these nanostructures, and (ii) multilayer structures containing close-to-critical Ge insertions in a Si matrix exhibiting strong photoluminescence at room temperature for the optimally grown samples.