| 摘要 |
PURPOSE:To make the ionization factor of electrons larger than the ionization factor of positive holes without fail and facilitate suppressing noise of a semiconductor photodetector by combining semiconductors which have conductivity types and the widths of forbidden bands corresponding to the ratio of the ionization factors of electrons and positive holes. CONSTITUTION:A multilayer structure in which 1st semiconductor layers 6-1 and 6-2 composed of n-type In0.53Ga0.47As layers in which ionization factor of electrons is larger than ionization factor of positive holes and 2nd semiconductor layers 2-1, 2-2 and 2-3 composed of p-type In0.52Al0.48As layers in which ionization factor of electrons is larger than ionization factor of positive holes and whose forbidden band width is wider than that of the 1st semiconductor layers are alternately laminated and a p<+>type region 4 and an n<+>type region 5, which are provided on both sides of the multilayer structure and function as a pair of electrodes which apply an electric field to the direction parallel to the surfaces of the 1st and 2nd semiconductor layers, are included in the constitution of the semiconductor photodetector. The thicknesses of the n-type In0.53Ga0.47As layers 6-1 and 6-2 and the p-type In0.52Al0.48As layer 2-2 are 1mum respectively and the thicknesses of the p-type In0.52Al0.48As layers 2-1 and 2-3 are 0.5mum respectively and doping concentrations of these layers are 5X10<15>X10<16>cm<-3>.
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