Abstract: A method and apparatus for contructing diamond semiconductor structures made of polycrystalline diamond thin films is disclosed. The use of a polycrystalline diamond deposition on a substrate material provides an advantage that any substrate material may be used and the ability to use polycrystalline diamond as a material is brought about through the use of an undoped diamond layer acting as an insulating layer which is formed on a boron-doped layer. Because of the structure, ion implantation can be employed to reduce the ohmic contact resistance. The ion implantation also provides that the entire structure can be made using a deep implant to form a channel layer which allows the insulating gate structure to be formed as an integral part of the device. The buried channel can be doped through the use of several implantation steps through the insulating undoped layer.