| 摘要 |
An object of the present invention is to provide, for example, a photodiode that can have sufficiently high sensitivity in a near-infrared wavelength range of 1.5 mum to 1.8 mum and can have a low dark current. A photodiode (10) according to the present invention includes a buffer layer (2) positioned on and in contact with an InP substrate (1), and an absorption layer (3) positioned on and in contact with the buffer layer, wherein the absorption layer includes 50 or more pairs in which a first semiconductor layer 3a and a second semiconductor layer 3b constitute a single pair, the first semiconductor layer 3a having a bandgap energy of 0.73 eV or less, the second semiconductor layer 3b having a larger bandgap energy than the first semiconductor layer 3a, and the first semiconductor layer 3a and the second semiconductor layer 3b constitute a strain-compensated quantum well structure and each have a thickness of 1 nm or more and 10 nm or less.
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