| 摘要 |
PURPOSE:To detect a plurality of lights whose wavelength ranges are different from each other by a method wherein a plurality of semiconductor layers which transmit the lights with wavelengths longer than predetermined wavelengths and the predetermined wavelengths of upper layer are shorter than those of lower layers. CONSTITUTION:1st semiconductor layer 1 is formed, for instance, on a GaAs n-type substrate by liquid phase growth of n-type GaAlAs whose ratio between Ga and Al is so controlled as to predetermine a wavelength lambdao1 which is to be a light wavelength limit in a sensitive region by determining a forbidden band width Eg1. Then a P-N junction is formed by diffusing a p-type impurity to display a photovoltaic effect which has a sensitive region in the wavelength range shorter than the predetermined wavelength lambdao1. At that time, the predetermined wavelength lambdao1 can be varied by varying the ratio between Ga and Al, e.g. the forbidden band width Eg1. Moreover, a specific sensitivity for a peak wavelength on the shorter wavelength side can be varied by controlling the depth of the impurity diffusion. In such case, the deeper the depth of the impurity diffusion, the lower the specific sensitivity on the shorter wavelength side.
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