| 摘要 |
PURPOSE:To increase ionization rate, and to reduce noises by making the discontinuous width of a conduction band between semiconductor layers constituting strain layer superlattice structure larger than that of a valence band. CONSTITUTION:An avalanche multiplication region 12 having strain layer superlattice structure in which N<-> type GaAs layers 12a and N<-> type InGaAs layers 12b are laminated alternately is formed on a P<+> type InP substrate 11. An N<-> type InGaAs optical absorption layer 13 and an N<+> type InP cap layer 14 are formed brought into contact with the strain layer superlattice structure 12. A semiconductor photodetector device is obtained by shaping an antireflection coating film 15, a surface protective film 16, an N type electrode 17 and a P type electrode 18. The discontinuous width of conduction bands among the layers 12a, 12b constituting the strain layer superlattice structure is made larger than that of a valence band at that time. |
