A semiconductor device is provided having a dual dielectric layer structure defined by a thin dielectric layer adjacent to a thick dielectric layer. More particularly, a high voltage metal oxide semiconductor transistor having a dual gate oxide layer structure comprising a thin gate oxide layer adjacent to a thick oxide/thin oxide layer may be provided. Such structures may be used in extended drain metal oxide semiconductor field effect transmitters, laterally diffused metal oxide field effect transistors, or any high voltage metal oxide semiconductor transistor. Methods of fabricating an extended drain metal oxide semiconductor transistor device are also provided.