| 摘要 |
PURPOSE:To obtain the titled element which has high speed responding characteristic and can ignore the influence of a capacity without loss of quantum efficiency by reducing valence band upper end energy absolute value and conduction band lower end energy absolute value of the alternately laminated first semiconductor at thermal balance time smaller than those of two semiconductors. CONSTITUTION:First and second semiconductor layers 3, 2 are alternately laminated a pair or more on a semi-insulating semiconductor substrate 1, and a pair of electrodes 5, 6 for applying voltage of the same potential from the uppermost layer to the lowermost layer of the laminated layers 3, 2 are provided. In such a photoconductive semiconductor photo detector, the valence band upper end energy absolute value at thermal balance time measured from the vacuum level of the first semiconductor 3 is reduced than that of the second semiconductor 2 and the conduction band lower end energy absolute value at thermal balance time measured from the vacuum level of the first semiconductor 3 is reduced than of the second semiconductor 2. A 3-layer structure that the second semiconductor GaAs0.5Sb0.5 layer 2, the first semiconductor In0.53Ga0.47 As layer 3 and the GaAs0.5Sb0.5 layer 2 are sequentially crystal-grown on a semi- insulating InP substrate 1 is, for example, formed so that the impurity densities and the thicknesses of the layers are 1X10<16>cm<-3> and 3,000Angstrom .
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