Patent ID: 7508015

Claim:
A semiconductor device comprising: a first semiconductor layer represented by a composition formula Al x Ga 1-x N (0≦x≦1); a first conductivity type or non-doped second semiconductor layer represented by a composition formula Al y Ga 1-y N (0≦y≦1, x<y), formed on the first semiconductor layer and having a concave portion; a second conductivity type third semiconductor layer represented by a composition formula Al x Ga 1-x N (0≦x≦1) and is selectively formed above a bottom surface of the concave portion of the second semiconductor layer; a gate electrode formed on the third semiconductor layer; a source electrode electrically connected to the second semiconductor layer; and a drain electrode electrically connected to the second semiconductor layer, wherein the third semiconductor layer is formed so as to coat the bottom surface of the concave portion, a side surface of the concave portion and a surface of a portion of the second semiconductor layer which is thicker than the concave portion.