Semiconductor devices including dual gate structures and methods of forming such semiconductor devices are disclosed. For example, semiconductor devices are disclosed that include a first gate stack that may include a first conductive gate structure formed from a first material, and a second gate stack that may include a dielectric structure formed from an oxide of the first material. For another example, methods including forming a high-K dielectric material layer over a semiconductor substrate, forming a first conductive material layer over the high-K dielectric material layer, oxidizing a portion of the first conductive material layer to convert the portion of the first conductive material layer to a dielectric material layer, and forming a second conductive material layer over both the conductive material layer and the dielectric material layer are also disclosed.