A method for forming a forming a silicon germanium tin (SiGeSn) layer is disclosed. The method may include, providing a substrate within a reaction chamber, exposing the substrate to a pre-deposition precursor pulse, which comprises tin tetrachloride (SnCl4), exposing the substrate to a deposition precursor gas mixture comprising a hydrogenated silicon source, germane (GeH4), and tin tetrachloride (SnCl4), and depositing the silicon germanium tin (SiGeSn) layer over a surface of the substrate. Semiconductor device structures including a silicon germanium tin (SiGeSn) layer formed by the methods of the disclosure are also provided.