Semiconductor device

A semiconductor device comprising:

• a sub-collector layer that is provided in a surface layer portion of a substrate and is electrically conductive, the sub-collector layer being surrounded by an insulating region when viewed in plan;
• a bipolar transistor that is located within the sub-collector layer when viewed in plan, the bipolar transistor including a collector layer, a base layer, and an emitter layer that are arranged in a stated order in a thickness direction, the collector layer being connected to the sub-collector layer;
• an emitter electrode that is long in a first direction when viewed in plan, the emitter electrode overlapping the emitter layer and being electrically connected to the emitter layer;
• a base electrode that is long in the first direction when viewed in plan, the base electrode and the emitter electrode being discretely located away from each other in a second direction orthogonal to the first direction, the base electrode being electrically connected to the base layer;
• a collector electrode that is located on one side in the second direction with respect to the emitter electrode and is not located on the other side when viewed in plan, the collector electrode being electrically connected to the collector layer via the sub-collector layer;
• and
• a base line connected to the base electrode in a manner so as to adjoin a portion other than longitudinal ends of the base electrode.