Abstract: In a base region of a first conductivity type, at least one emitter region of a second conductivity type and at least one sense region of the second conductivity type, spaced away from the emitter region, are selectively formed. The emitter region and the sense region are located so as to be aligned in a second direction perpendicular to a first direction going from a collector region of the first conductivity type, which is formed so as to be spaced away from the base region, toward the base region. The width of the sense region, the width of the emitter region, the width of a part of the base region that is adjacent to the sense region, and the width of a part of the base region that is adjacent to the emitter region in the second direction are set in such a manner that a sense ratio varies in a desired manner in accordance with variation in collector current.

Abstract: A method of fabricating a semiconductor device with a composite contact is provided. The fabrication includes forming the composite contact to a semiconductor layer in a semiconductor structure. The composite contact is formed by forming a DC conducting electrode attached to a semiconductor layer in a semiconductor structure and forming a capacitive electrode that is partially over the DC conducting electrode and extends beyond the DC conducting electrode. The composite contact provides a combined resistive-capacitive coupling to the semiconductor layer. As a result, a contact impedance is reduced when the corresponding semiconductor device is operated at high frequencies.

Abstract: A method of fabricating a semiconductor device with a composite contact is provided. The fabrication includes forming the composite contact to a semiconductor layer in a semiconductor structure. The composite contact is formed by forming a DC conducting electrode attached to a semiconductor layer in a semiconductor structure and forming a capacitive electrode that is partially over the DC conducting electrode and extends beyond the DC conducting electrode. The composite contact provides a combined resistive-capacitive coupling to the semiconductor layer. As a result, a contact impedance is reduced when the corresponding semiconductor device is operated at high frequencies.

Abstract: A high-frequency switching transistor comprises a collector area, which has a first conductivity type, a first barrier area bordering on the collector area, which has a second conductivity type which differs from the first conductivity type, and a semiconductor area bordering on the first barrier area, which has a dopant concentration which is lower than a dopant concentration of the first barrier area. Further, the high-frequency switching transistor has a second barrier area bordering on the semiconductor area, which has a first conductivity type, as well as a base area bordering on the second barrier area, which has a second conductivity type. Additionally, the high-frequency switching transistor comprises a third barrier area bordering on the semiconductor area, which has the second conductivity type and a higher dopant concentration than the semiconductor area. Further, the high-frequency switching transistor has an emitter area bordering on the third barrier area, which has the first conductivity type.