A photodiode has a substrate. A mesa structure is formed on the substrate, wherein the mesa structure has an n region containing an n type dopant formed on the substrate, an intermediate region positioned on the n region and a p region formed on the intermediate region and containing a p type dopant. A contact is formed on a top surface of the mesa and attached to the p region. The contact is formed around an outer perimeter of the mesa. The mesa has a diameter of 30 um or less.

A photodetecting device includes a semiconductor substrate, a plurality of avalanche photodiodes each having a light receiving region, the avalanche photodiodes being arranged in a matrix at the semiconductor substrate, and a plurality of through-electrodes electrically connected to corresponding light receiving regions. The plurality of through-electrodes are arranged for each area surrounded by four mutually adjacent avalanche photodiodes of the plurality of avalanche photodiodes. Each of the light receiving regions has, when viewed from a direction perpendicular to a first principal surface of the semiconductor substrate, a polygonal shape including a pair of first sides opposing each other in a row direction and extending in a column direction and four second side opposing four through-electrodes surrounding the light receiving region and extending in directions intersecting with the row direction and the column direction. The length of the first side is shorter than the length of the second side.

A sensor may be provided, including a substrate having a first semiconductor layer, a second semiconductor layer, and a buried insulator layer arranged between the first semiconductor layer and the second semiconductor layer. The sensor may further include a photodiode arranged in the first semiconductor layer; and a quenching resistive element electrically connected in series with the photodiode. The quenching resistive element is arranged in the second semiconductor layer, and the quenching resistive element is arranged over the photodiode but separated from the photodiode by the buried insulator layer.

A ultraviolet detector includes a substrate; a first epitaxial layer that is a heavily doped epitaxial layer and located on the substrate, a second epitaxial layer located on the first epitaxial layer, where the second epitaxial layer is a lightly doped epitaxial layer, or a double-layer or multi-layer structure composed of at least one lightly doped epitaxial layer and at least one heavily doped epitaxial layer; an ohmic contact layer located on the second epitaxial layer or formed in the second epitaxial layer, where the ohmic contact layer is a graphical heavily doped layer; and a first metal electrode layer located on the ohmic contact layer.

A photodetecting device includes a semiconductor substrate, a plurality of avalanche photodiodes each including a light receiving region disposed at a first principal surface side of the semiconductor substrate, the avalanche photodiodes being arranged two-dimensionally at the semiconductor substrate, and a through-electrode electrically connected to a corresponding light receiving region. The through-electrode is provided in a through-hole penetrating through the semiconductor substrate in an area where the plurality of avalanche photodiodes are arranged two-dimensionally. At the first principal surface side of the semiconductor substrate, a groove surrounding the through-hole is formed between the through-hole and the light receiving region adjacent to the through-hole. A first distance between an edge of the groove and an edge of the through-hole surrounded by the groove is longer than a second distance between the edge of the groove and an edge of the light receiving region adjacent to the through-hole surrounded by the groove.

A method for preparing an avalanche photodiode includes preparing a mesa on a wafer, growing a sacrificial layer on an upper surface of the wafer and a side surface of the mesa, removing the sacrificial layer in an ohmic contact electrode region of the wafer, preparing an ohmic contact electrode in the ohmic contact electrode region of the wafer, removing the sacrificial layer in a non-mesa region of the wafer, growing a passivation layer on the upper surface of the wafer and the side surface of the mesa, removing the passivation layer on the upper surface of the mesa of the wafer and the passivation layer in the non-mesa region of the wafer corresponding to the ohmic contact electrode region, and removing the sacrificial layer on the upper surface of the mesa of the wafer.

Provided is a semiconductor light receiving element which can achieve a high-speed operation without sacrificing light receiving sensitivity while increasing the margin of a manufacturing process. The semiconductor light receiving element according to the present invention is characterized by comprising: a semiconductor layer doped with a first impurity; a semiconductor light absorption layer in which a band gap energy is adjusted to absorb incident light on the semiconductor layer doped with the first impurity; a semiconductor layer on the semiconductor light absorption layer and doped with a second impurity; and a metal electrode contacting side surfaces of the semiconductor layer doped with the second impurity, wherein side surfaces of the metal electrode are surfaces parallel to a growth direction of the semiconductor layer doped with the second impurity.

A photosensitive element includes a semiconductor substrate, a light sensitive region formed in the semiconductor substrate, an inactive region at least partly surrounding the light sensitive region, and a protective layer having an opening leaving the light sensitive region uncovered by the protective layer. The protective layer is an anti-reflective coating having in at least a part of a spectral range between 300 nm and 1200 nm a reflectivity of less than 10% and a transmittance of less than 0.1%.

A photodetector comprising: a separation region that is provided in a semiconductor substrate and defines a pixel region; a hole accumulation region that is provided in the semiconductor substrate of the pixel region along a side surface of the separation region; a multiplication region that is provided in the semiconductor substrate of the pixel region and is configured by joining a first conductivity type region and a second conductivity type region from the surface side of the semiconductor substrate in the thickness direction of the semiconductor substrate; and an insulating region provided in the semiconductor substrate in a region between the multiplication region and the hole accumulation region, wherein a formation depth of the insulating region is larger than a formation depth of the first conductivity type region.

A semiconductor substrate has a first surface and a second surface which is opposite to the first surface. A photoelectric conversion portion has a PN junction configured with first and second semiconductor regions of different conductivity types. A buried portion is buried in the semiconductor substrate and includes an electrode and a dielectric member located between the electrode and the semiconductor substrate and in contact with the second semiconductor region. The second semiconductor region is located in a position deeper than the first semiconductor region. The buried portion is located to extend from a first surface to a position deeper than the first semiconductor region. Electric potentials are supplied to the first semiconductor region, the second semiconductor region, and the electrode in such a manner that an inversion layer occurring between the electrode and the second semiconductor region and the first semiconductor region are in contact with each other.