Morphological properties of laser irradiated Si/Ge multilayers

Si/Ge multilayers with a total thickness of 65 nm were grown by molecular beam epitaxy (MBE) and treated with pulsed Nd:YAG laser (1.06 μm) irradiation. Using transmission electron microscopy (TEM) clear evidence is found that the Si/Ge multilayers contain nanoislands after irradiation. Depending on the conditions of laser irradiation the average size and density of the nanoislands vary within 4-12 nm and 8.7×109-5.8×1010 cm−2. Rutherford backscattering spectroscopy (RBS) demonstrates that no visible redistribution of Ge and Si takes place after laser irradiation. The results are discussed in terms of depression of melting point.