Detection and characterization of individual Ge layers in Si(100) using Raman spectroscopy

The Raman active vibrational modes of single, 1 to 6 layer thick Ge films grown epitaxially on Si(100) and covered by thin layers of Si(100) have been measured. Both the Ge-Ge vibrations from the interior of the Ge films and the Ge-Si vibrations at the Ge-Si interfaces have been observed. These modes and the weak defect activated scattering are used to characterize the Ge layers. These results show that Raman spectroscopy can now be used to directly characterize the properties of buried interfaces at the level of single atomic layers.