Patent attributes
To reduce a variation in the characteristics of avalanche photodiode sensors. An avalanche photodiode sensor includes a first semiconductor region, a second semiconductor region, a low-impurity-concentration region, a first contact region, and a second contact region. The first semiconductor region is disposed on a surface of a semiconductor substrate. The second semiconductor region is disposed below the first semiconductor region and has a different conductivity type from the first semiconductor region. The low-impurity-concentration region is disposed adjacent to the second semiconductor region. The first contact region is disposed on the surface of the semiconductor substrate to be adjacent to the first semiconductor region and has electrodes connected thereto. The second contact region is disposed adjacent to the low-impurity-concentration region and has electrodes connected thereto.
