HEMT device with crystallinity control film

A semiconductor device comprising:

• a substrate;
• a semiconductor layer disposed on the substrate;
• an insulating layer disposed on the semiconductor layer and having a first opening formed therein;
• a gate electrode disposed on the insulating layer and in contact with the semiconductor layer via the first opening;
• and
• a source electrode and a drain electrode in ohmic contact with the semiconductor layer,
• wherein the gate electrode includes:
• a ZnO film disposed on the insulating layer and having a second opening formed such that an inner wall thereof extends to an inner wall of the first opening;
• a Ni film disposed on the ZnO film and in Schottky contact with the semiconductor layer via the inner walls, extending to each other, of the second opening and the first opening;
• and
• an Au film disposed on the Ni film and having a lower electrical resistance than the Ni film.

A semiconductor device comprising:

• a substrate;
• a semiconductor layer disposed on the substrate;
• an insulating layer disposed on the semiconductor layer and having a first opening formed therein;
• a gate electrode disposed on the insulating layer and in contact with the semiconductor layer via the first opening;
• and
• a source electrode and a drain electrode in ohmic contact with the semiconductor layer,
• wherein the gate electrode includes:
• a crystallinity control film disposed on the insulating layer and having a second opening formed such that an inner wall thereof extends to an inner wall of the first opening toward the substrate in plan view in a direction perpendicular to a top surface of the substrate,
• a first metal film disposed on the crystallinity control film and in Schottky contact with the semiconductor layer via the inner walls, extending to each other, of the second opening and the first opening and
• a second metal film disposed on the first metal film and having a lower electrical resistance than the first metal film, and
• wherein a thickness of the crystallinity control film is 10 nm to 30 nm and the crystallinity control film includes a ZnO film, a GaN film, a Ti film, a TiN film, an Al film, an AlSiCu film, or an AlN film.