A semiconductor device, its manufacturing method, and a radiation measurement method are presented, relating to semiconductor techniques. The semiconductor device includes: a substrate comprising a base area and a collector area adjacent to each other; a plurality of semiconductor fins on the substrate, wherein the plurality of semiconductor fins comprises at least a first semiconductor fin and a second semiconductor fin on the base area and separated from each other, the first semiconductor fin comprises an emission area adjacent to the base area, and the second semiconductor fin comprises a first region adjacent to the base area; a first gate structure on the second semiconductor fin; and a first source and a first drain at two opposite sides of the first gate structure and at least partially in the first region. Radiation in a semiconductor apparatus can be measured through this semiconductor device.