| CPC H10F 39/8033 (2025.01) [H10F 39/18 (2025.01)] | 16 Claims |
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1. A photodetector comprising:
a semiconductor substrate including a first principal surface and a second principal surface that is opposite to the first principal surface in a thickness direction of the semiconductor substrate; and
at least two or more avalanche photodiodes (APDs) formed in the semiconductor substrate, wherein:
a first region is arranged outside the APDs as viewed in plane,
adjacent ones of the APDs and the first region are separated from each other through a separation region,
each APD includes a first semiconductor layer of a second conductive type included in the semiconductor substrate and a fourth semiconductor layer of a first conductive type contacting the first semiconductor layer,
the first region includes the first semiconductor layer and a fifth semiconductor layer of the first conductive type contacting the first semiconductor layer,
a first voltage V21 is applied to the fourth semiconductor layer of each APD, and a second voltage V22 is applied to the fifth semiconductor layer of the first region,
the first voltage V21 is higher than the second voltage V22,
a third voltage Vrev is applied to the second principal surface,
the first voltage V21, the second voltage V22, and the third voltage Vrev are controlled so that a difference between a first reverse bias V1 to be applied to each APD and a second reverse bias V2 to be applied to the first region is smaller than a difference in potential between the separation region and the first region, and
following relationships are satisfied:
|V1|=V21+|Vrev| (1), and
|V2|=V22+|Vrev| (2).
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