Optical detection device and ranging system

Abstract

The objective of this invention is to reduce dark current in the carrier transport path. The photodetector of this invention includes: a substrate; a light-receiving portion disposed on the substrate, comprising a first semiconductor material, which generates charge based on incident light through photoelectric conversion; a multiplier portion disposed separately from the light-receiving portion in a first direction, which amplifies the charge generated in the light-receiving portion; and a first semiconductor region comprising the first semiconductor material and a second semiconductor material with a larger band gap than the first semiconductor material, which transfers the generated charge to the multiplier portion; and the first semiconductor region having a concentration gradient of the first semiconductor material that changes stepwise or continuously in the first direction.

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