Embodiments of the invention generally relate to methods for forming silicon-germanium-tin alloy epitaxial layers, germanium-tin alloy epitaxial layers, and germanium epitaxial layers that may be doped with boron, phosphorus, arsenic, or other n-type or p-type dopants. The methods generally include positioning a substrate in a processing chamber. A germanium precursor gas is then introduced into the chamber concurrently with a stressor precursor gas, such as a tin precursor gas, to form an epitaxial layer. The flow of the germanium gas is then halted, and an etchant gas is introduced into the chamber. An etch back is then performed while in the presence of the stressor precursor gas used in the formation of the epitaxial film. The flow of the etchant gas is then stopped, and the cycle may then be repeated. In addition to or as an alternative to the etch back process, an annealing processing may be performed.