The present invention provides methods, systems, and apparatus for epitaxial film formation that includes an epitaxial chamber adapted to form an epitaxial layer on a substrate; a deposition gas manifold adapted to supply at least one deposition gas and a carrier gas to the epitaxial chamber; and an etchant gas manifold, separate from the deposition gas manifold, and adapted to supply at least one etchant gas and a carrier gas to the epitaxial chamber. Numerous other aspects are disclosed.