Ohmic contact formation for n-type diamond by selective doping

Ohmic contacts with low contact resistivity were formed on phosphorus-doped n-type {111} diamond thin films grown by microwave-plasma chemical-vapor deposition. Heavily-doped diamond layers were selectively grown on a diamond substrate by covering a part of substrate surface with a titanium/gold layer. Gold contacts deposited directory on a lightly phosphorus-doped diamond showed a rectification characteristic, while those formed on the selectively grown, heavily doped diamond layers showed an Ohmic characteristic. The Ohmic property of contacts formed with the heavily doped layers was found to be independent of the metals. It is therefore concluded that the tunneling current dominates carrier transport at the interface between the metal and the heavily doped n-type diamond.