Methods for an oxide layer over an epitaxial layer. In an embodiment, a method includes forming an epitaxial layer of semiconductor material over a semiconductor substrate; forming an oxide layer over the epitaxial layer; applying a solution including an oxidizer to the oxide layer; and cleaning the oxide layer with a cleaning solution. In another embodiment, a densification process is applied to an oxide layer including treating with thermal energy, UV energy, or both. In an embodiment for a gate-all-around device, the cleaning process is applied to an oxide layer over an epitaxial portion of a fin. Additional methods are disclosed.