| 摘要 |
PURPOSE:To reduce the size of a device by constituting a light wavelength detector by using a photoelectric converting element and inverting the direction of an output current about specific critical wavelength. CONSTITUTION:A semiconductor element 5 has 1st and 2nd p-n junctions 10 and 11 formed integrally in series and in the opposite directions. The critical length is varied by varying the thickness D7 of an n-type semiconductor 7 and the material of the element 5. When light beams which are nearly as intense as each other are incident on the junctions 10 and 12 of this element 5, the electromotive force at the junction 11 is larger than that at the junction 10. When light 3 incident from the side of the junction 10 has short wavelength, sufficient light does not reach the junction 11. A current, therefore, flows to an external load 6 as shown by an arrow B. When the light 3 has long wavelength, on the other hand, light beams of nearly the same intensity are incident on the junctions 10 and 11. A current, therefore, flows to the load 6 as shown by C, so whether the wavelength is long or short is detected.
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