Patent ID: 8008749

Claim:
A semiconductor device comprising: a first electrode; a first conductor layer formed on the first electrode, the first conductor layer being made of a semiconductor material with a uniform concentration of impurities along a thickness direction and being in ohmic contact with the first electrode; an electric current regulation layer covering a part of a surface of the first conductor layer and leaving a non-covered surface at the surface of the first conductor layer; a semiconductor layer covering a surface of the electric current regulation layer; a conducting region connecting the semiconductor layer to the first conductor layer at the non-covered surface; a control electrode facing an intermediate portion of the semiconductor layer, the intermediate portion being separated laterally from the non-covered surface by a first portion of the semiconductor layer, the first portion extending vertically from a surface of the electric current regulation layer to a top surface of the semiconductor layer; and a second electrode formed at a surface of the semiconductor layer, the second electrode being located at a position separated laterally from the non-covered surface, wherein a semiconductor structure constructed by a plurality of semiconductor regions is formed within the semiconductor layer, a depletion layer is disposed within the first portion at non-conduction state, and the first portion has a length extending between the intermediate portion and the non-covered surface, the length being at least three times greater than a thickness of the first portion.