Photodiode and photodiode array

A back-illuminated type photodiode array in which a plurality of photodetecting channels for detection target light to be entered thereinto are formed on a silicon substrate having a semiconductor layer of a first conductivity type, the photodiode array comprising:

• an epitaxial semiconductor layer of a second conductivity type formed on the semiconductor layer of the first conductivity type, forming pn junctions at an interface to the semiconductor layer, and having a plurality of multiplication regions for avalanche multiplication of carriers generated with incidence of the detection target light, so that the multiplication regions correspond to the respective photodetecting channels;
• and
• a plurality of resistors each having two end portions, provided for the respective photodetecting channels, and each electrically connected through one of the end portions to the epitaxial semiconductor layer and connected through the other of the end portions to a signal conducting wire,
• wherein an irregular asperity is formed in at least a surface corresponding to the photodetecting channels in the semiconductor layer of the first conductivity type,
• wherein at least the surface corresponding to the photodetecting channels in the semiconductor layer of the first conductivity type is optically exposed, and
• wherein the surface where the irregular asperity is formed constitutes a light incident surface, light incident from the surface travels in the silicon substrate.

A back-illuminated type photodiode array in which a plurality of photodetecting channels for detection target light to be entered thereinto are formed on a silicon substrate having a semiconductor layer of a first conductivity type, the photodiode array comprising:

• an epitaxial semiconductor layer of the first conductivity type formed on the semiconductor layer of the first conductivity type, and having a plurality of multiplication regions for avalanche multiplication of carriers generated with incidence of the detection target light, so that the multiplication regions correspond to the respective photodetecting channels;
• a semiconductor region of a second conductivity type formed in the epitaxial semiconductor layer of the first conductivity type and forming pn junctions at an interface to the epitaxial semiconductor layer;
• and
• a plurality of resistors each having two end portions, provided for the respective photodetecting channels, and each electrically connected through one of the end portions to the semiconductor region of the second conductivity type in the epitaxial semiconductor layer and connected through the other of the end portions to a signal conducting wire,
• wherein an irregular asperity is formed in at least a surface corresponding to the photodetecting channels in the semiconductor layer of the first conductivity type,
• wherein at least the surface corresponding to the photodetecting channels in the semiconductor layer of the first conductivity type is optically exposed, and
• wherein the surface where the irregular asperity is formed constitutes a light incident surface, light incident from the surface travels in the silicon substrate.