Schottky barrier diode

A Schottky barrier diode, comprising:

• a semiconductor layer of a first conductivity type comprising a wide-bandgap semiconductor and a trench defining a mesa portion on a first surface thereof;
• a high-resistance region under the trench of the semiconductor layer, the high-resistance region comprising an impurity of a second conductivity type different from the first conductivity type;
• an insulating film or a semiconductor film of the second conductivity type, the insulating film or semiconductor film covering at least a bottom surface among inner surfaces of the trench;
• an anode electrode on the semiconductor layer through the insulating film or the semiconductor film, the anode electrode being connected to the mesa portion;
• and
• a cathode electrode directly or through another layer on a second surface of the semiconductor layer on the opposite side to the first surface, wherein a relationship W×Nd<D×Na is satisfied, where W is a width of a depletion layer formed in the semiconductor layer from the bottom surface of the trench in a depth direction when a reverse voltage is applied, Nd is a donor concentration in the high-resistance region, D is a depth of the high-resistance region from the bottom surface of the trench, and Nd is an acceptor concentration in the high-resistance region.