pressure cvd lpcvd ultra high vacuum cvd uhvcvd by molecular beam epitaxy mbe or by atomic layer deposition ald the epitaxial growth system may be a single wafer or multiple wafer batch reactor the growth system also may utilize low energy plasma to enhance the layer growth kinetics suitable cvd systems commonly used for volume epitaxy in manufacturing applications include for example epi centura single wafer multi chamber systems available from applied materials of santa clara calif or epsilon single wafer epitaxial reactors available from asm international based in bilthoven the netherlands in the cvd process obtaining epitaxial growth typically involves introducing a source gas into the chamber the source gas may include at least one precursor gas and a carrier gas such as for example hydrogen in those embodiments of the invention where the layers are formed from si silicon precursor gases such as for example silane disilane trisilane or dichlorosilane dcs trichlorosilane tcs or silicon tetrachloride may be used conversely in those embodiments of the invention where the layers are formed from ge germanium precursor gases such as for example germane geh 4 digermane germanium tetrachloride or dichlorogermane or other ge containing precursors may be used finally in the embodiments where the layers are formed from sige alloy a combination of silicon and germanium precursor gases in various proportions is used in an embodiment in which the strained layer 102 contains substantially 100 si the strained layer 102 may be formed in a dedicated chamber of a deposition tool that is not exposed to ge source gases thereby avoiding cross contamination and improving the quality of the interface 108 between the strained layer 102 and the.