Determining Si1-xGex layer thickness and composition by ellipsometry

The thickness and composition of Si_1-xGe_x layers deposited on silicon substrates can be determined by optical ellipsometry after suitable calibration by other means, such as Rutherford backscattering. The technique is sensitive to a few tenths of a nanometre native oxide on the surface of the Si_1-xGe_x layer (primarily affecting Delta ), and this oxide must be considered in using the technique.