SPECTROELLIPSOMETRIC CHARACTERIZATION OF THIN EPITAXIAL SI(1-X)GE(X)LAYERS

Spectroscopic ellipsometry is assessed as a tool for rapid and non-des tructive determination of thicknesses and/for Ge concentrations of Si1 -xGex epitaxial layers. Ail algorithm for the extraction of optical co nstants from ellipsometric measurements carried out on strained uncapp ed Si1-xGex layers is developed. The smoothness of the extracted spect ra of the Si0.92Ge0.08 optical constants indicates very high accuracy even in the region of the weak absorption. Spectroscopic ellipsometry measurements of Si capped Si1-xGex layers are interpreted using the es tablished reference data and correlated with results from other techni ques. The accuracy of this interpretation for the spectroellipsometric zetric determination of Ge concentration and Si1-xGex layer thickness is numerically predicted. It is suggested that spectroscopic ellipsome try can also be applied to capped Si1-xGex layers if more accurate ref erence data in the low absorption legion become available.