Raman and Fourier transform infrared study of substitutional carbon incorporation in rapid thermal chemical vapor deposited Si1−x−yGexCy on (1 0 0) Si

Abstract

We report on a detailed study of the dependence of the vibrational modes in rapid thermal chemical vapor deposited Si1−x−yGexCy films on the substitutional carbon concentration. Si1−x−yGexCy films were investigated using Raman and infrared spectroscopy with x varying in the range of 10%–16% and y in the range of 0%–1.8%. The introduction of C into thin SiGe layers reduces the average lattice constant. It has been shown that the integrated infrared intensity of the Si–C peak and the ratio of both the Raman integrated and peak intensities of the Si–C peak (at ∼605 cm−1) to the Si–Si peak of SiGeC layer, increase linearly with C content and are independent of the Ge content. This leads to the conclusion that infrared absorption and Raman scattering data can be used to determine the fraction of substitutional carbon content in Si1−x−yGexCy layers with a Ge content of up to 16%. It is also shown that the intensity ratio of the carbon satellite peak to the local carbon mode increases linearly with C content up to a C level of 1.8%. This confirms a conclusion of an increase in the probability of creating third-nearest-neighbor pairs with increasing carbon content, as derived from theoretical calculations.