Device scaling and new applications in nanoelectronics present increasing challenges to epitaxy. Reducing thermal budgets, compatibility with novel materials, increasing topology and higher device density require new strategies for both the epitaxial film growth itself and substrate preparation. In this talk we will review specific problems for enabling low temperature epitaxial growth and discuss the impact of non-volatile contaminants beyond oxygen on Si and SiGe epitaxy. We will compare multiple potential solutions and discuss their utility and limitations.