Patent ID: 7872285

Claim:
A vertical gallium nitride semiconductor device furnished with: a gallium nitride support base of n + -type conductivity, therein having a given carrier concentration; a gallium nitride epitaxial film of n − -type conductivity provided on a principal surface of said gallium nitride support base, therein defining an interface between said gallium nitride support base and said gallium nitride epitaxial film; a laminar region, of not greater than 1 μm thickness, including the interface between said gallium nitride support base and said gallium nitride epitaxial film, where either said gallium nitride support base or said gallium nitride epitaxial film has at least either silicon or germanium as donor impurities at a concentration, along an axis from said gallium nitride support base to said gallium nitride epitaxial film, of not less than 1×10 18 cm −3 , wherein the presence of magnesium, beryllium, calcium, zinc, or cadmium as unintentional impurities in the vertical gallium nitride semiconductor device assumes a concentration profile whose peak resides in said laminar region; a gate insulating film provided on said gallium nitride epitaxial film; a gate electrode provided on said gate insulating film; a p-type conductivity region provided on said gallium nitride epitaxial film; an n + -type conductivity region provided in said p-type conductivity region; a source electrode provided on said n + -type conductivity region of said gallium nitride epitaxial film; and a drain electrode provided on a back side of said gallium nitride support base.