PURPOSE: To reduce a leakage current in a reverse direction by a method wherein impurity concentration in an n-layer under a Schottky electrode is reduced sufficiently to reduce a capacitance value, and an impurity region whose concentration is close to that in an n+ layer is formed between a high-concentration impurity region on the side of an ohmic electrode and the Schottky electrode so that its thickness can be thinner than that of the n+ layer.

CONSTITUTION: An SiO2 thin film 35 is formed on a GaAs semiinsulating substrate 5; a photoresist 31 is applied to it. A window is opened at the photoresist; ions are implanted; an n-layer 32 is formed. Then, an electrode metal tungsten silicide film to be used as a Schottky electrode 4 of a diode or as a gate of a transistor is applied; an electrode metal is processed. Then, this assembly is covered with an SiO2 film 36; an n' layer 2 is formed. In this case, the n' layer 2 is formed in a manner which is self-aligned with the electrode metal. Then, the photoresist 31 is removed; after that, this assembly is etched in such a way that the SiO2 film is left only at a side part of the Schottky electrode 4; a side wall 10 is formed; one part is covered with the photoresist 31; an n+ layer 3 is formed. In addition, AuGe, Ni and Au are deposited on a part where the window has been opened. This assembly is heat-treated and alloyed; an ohmic electrode 6 is formed.