| 摘要 |
PURPOSE:To improve reflection preventing effect and detection efficiency of incident light on a light receiving surface, by forming an upper reflection preventing film, whose refractive index Nb is higher than that of silicon dioxide and thickness is odd number times of lambda/4Nb, on the upper part of a lower reflection preventing film. CONSTITUTION:A lower reflection preventing film 7a', whose refractive index is Na, is formed at the junction part of a P layer part of a substrate 1 by a thermal oxidation method of silicon dioxide, in such a way that the thickness Da' of said reflection preventing film 7a' is integer times of lambda/2Na of the wavelength lambda of light 8'. An upper reflection preventing film 7b has a higher refractive index Nb than that of silicon diode. The film 7b is formed on the lower reflection preventing film 7a', in such a way that the thickness Db of the reflection preventing film 7b is odd number times of lambda/4Nb of the wavelength lambda of the light 8'. The highest reflection preventing effect is obtained in correspondence with the refractive index Nx of a substrate 1 and the refractive index Ny of an atmosphere. |
