Abstract: A photodetection device is provided which includes a pixel array unit including a plurality of pixels arranged in a matrix on a semiconductor substrate to detect light, in which each of the pixels includes a pixel separation wall that surrounds the pixels and separates the pixels from one another, a photoelectric conversion unit inside the semiconductor substrate to generate an electric charge by light, a multiplication region inside the semiconductor substrate to multiply the electric charge from the photoelectric conversion unit, and first and second reflective portions that reflect light traveling toward outside the semiconductor substrate into the semiconductor substrate, the first reflective portion is provided, on a first surface that receives light of the semiconductor substrate, to protrude from the pixel separation wall toward a pixel center, and the second reflective portion is provided on a second surface of the semiconductor substrate facing the first surface.

Abstract: 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.

Abstract: 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.