Semiconductor device and method for producing same

A method for producing a semiconductor comprising a GaN device including:

• a substrate made of a semi-insulating material or a semiconductor;
• a channel forming layer including a GaN layer arranged on the substrate;
• a gate structure having a gate insulating film in contact with the GaN layer and arranged on the channel forming layer, and a gate electrode arranged via the gate insulating film;
• and
• a source electrode and a drain electrode that are arranged on opposite sides to interpose the gate structure, on the channel forming layer, the method comprising:
• forming the channel forming layer that includes the GaN layer on the substrate;
• forming the gate insulating film that is in contact with the GaN layer on the channel forming layer;
• and
• removing donor elements present in a portion of the GaN layer that is in contact with the gate insulating film after forming the channel forming layer and before forming the gate insulating film,
• wherein the gate insulating film is formed without being exposed to an atmosphere containing the donor elements after removing the donor elements.