Semiconductor device and radio frequency power amplifier

A semiconductor device, comprising:

• a substrate;
• a transistor including a collector layer, a base layer, and an emitter layer that are laminated in order on an upper surface being one side surface of the substrate;
• four or more emitter electrodes electrically coupled to the emitter layer;
• a base electrode including two or more base fingers electrically coupled to the base layer;
• and
• a collector electrode electrically coupled to the collector layer,
• wherein
• the emitter electrodes and the base fingers each have a shape elongated in a first direction in the upper surface of the substrate,
• the emitter electrode and the base finger are side by side in a second direction orthogonal to the first direction in the upper surface of the substrate,
• emitter electrodes are respectively at both ends in the second direction of a row in which the four or more emitter electrodes and the two or more base fingers that are side by side in the second direction,
• an inter-base finger region is a region between the two base fingers adjacent to each other in the second direction, and the two emitter electrodes being side by side in the second direction are in at least the one inter-base finger region, and
• when a ratio of an area of the emitter electrode in plan view to a length of an edge of the emitter electrode facing the one or two base fingers that are adjacent to each of multiple of the multiple electrodes is defined as an area to facing length ratio, a difference between a maximum value and a minimum value of the area to facing length ratio of each of the multiple emitter electrodes is 20% or less of an average value of the area to facing length ratio.