| 摘要 |
PROBLEM TO BE SOLVED: To achieve improvement in sensitivity across an entire use wavelength band required and inhibition of reduction in a frequency response bandwidth.SOLUTION: In a photodiode, at least one of a layer thickness and a complex refractive index of each of a first semiconductor layer 102, a light-absorption layer, a second semiconductor layer 104 and a reflection layer 108 is set such that a phase difference &Dgr; between two partial waves E1, E2 which have an optical path difference by one bounce of light which is incident from the side of a substrate 101 and bounces between the reflection layer 108 and the first semiconductor layer 102 becomes &pgr;/4+2 N&pgr;≤&Dgr;≤3&pgr;/4+2 N&pgr; (N is an integer) at a center wavelength of a target wavelength. |
