The effect of postgrowth annealing on the structure and optical properties of multilayer Ge/Si heterostructures

The effect of the postgrowth laser and thermal annealing on the structure and optical properties of multilayer heterostructures comprising quantum dots of germanium in a silicon matrix has been studied by photoluminescence (PL) and transmission electron microscopy (TEM). The PL spectra of annealed samples reveal a decrease of emission from the quantum dots and display a new emission band as compared to the initial spectra. The TEM measurements show that this effect is related to smearing of the Ge-Si interface and to the appearance of a regular rectangular network of dislocations on the surface of the annealed structure.