Patent ID: 8487319

Claim:
A diamond semiconductor element having a gate electrode, a source electrode and a drain electrode each formed directly on a diamond single-crystal thin-film at a distance from each other, wherein said gate electrode includes fifth and sixth end faces perpendicular to the diamond single-crystal thin-film, said source electrode includes a first area extending from a bottom surface close to said diamond single-crystal thin-film to a top surface; and a second area above the top surface of the first area, the first and second areas respectively having first and second end faces generally facing the fifth end face, where a first distance (d SGB ) between the first end face and the fifth end face is less than a second distance (d SGT ) between the second end face and the fifth end face, and where the first distance (d SGB ) is greater when measured at the bottom surface of the first area than at the top surface of the first area, the first and second distances being measured in a direction parallel to the diamond single-crystal thin-film, and said drain electrode includes a third area extending from a bottom surface close to said diamond single-crystal thin-film to a top surface; and a fourth area above the top surface of the third area, the third and fourth areas respectively having third and fourth end faces generally facing the sixth end face, where a third distance (d GDB ) between the third end face and the sixth end face is less than a fourth distance (d GDT ) between the fourth end face and the sixth end face, and where the third distance (d GDB ) is greater when measured at the bottom surface of the third area than at the top surface of the third area, the third and fourth distances being measured in a direction parallel to the diamond single-crystal thin-film, wherein there is no part of the diamond semiconductor element between the first to fourth end faces and the gate electrode.