layer may be increased in addition to improving deposition rate the catalytic effect of germanium ge also provides for epitaxial growth of a csa layer at a lower deposition temperature range this promotes the incorporation of substitutional carbon in the silicon si lattice leading to increased substituted carbon c in epitaxially grown csa layer fig5 a illustrates a graph showing the respective number of carbon c oxygen o and silicon si atoms per units volume in a csa layer grown on a silicon substrate where epitaxial growth is performed in the absence of germanium from fig5 a the depth of the csa layer in a sample not shown is approximately 49 nm with a percentage of substituted carbon at approximately 87 fig5 b illustrates a graph showing the respective number of carbon c germanium ge oxygen o and silicon si per unit volume in a csa layer 500 fig3 grown on silicon substrate 100 fig3 where germanium is introduced during epitaxial growth process s 4 from fig5 b the percentage of substitutional carbon in csa layer 500 fig3 may be as high as approximately 96 with the depth of csa layer 500 reaching approximately 100 nm by introducing trace amount of approximately 2 23 u00d7 10 20 atoms cm 3 i e approximately 0 45 of germane the percentage of substituted c in the si lattice is increased by approximately 10 in process s 5 csa layer 500 as shown in fig3 is etched to remove any growth on non silicon sites 600 on the substrate 100 the etchant may include for example but not limited to chlorine hydrogen chloride or a combination thereof process s 6 is a cyclic.