| 摘要 |
PROBLEM TO BE SOLVED: To obtain a semiconductor laser which is operable with a low threshold current by bringing a quantum-well layer into undoped state of intrinsic carrier concentration of a specified level or less and forming a barrier layer of a semiconductor layer of negative or positive conductivity type having a carrier concentration of a specified level or above. SOLUTION: An n-type InP buffer layer 102, a strained multiple quantum-well active layer 105 where a multiple quantumwell layer is sandwiched by an n-type InGaAsP lower guide layer and an InGaAs upper optical guide layer, a p-type InP clad layer 106 and a high concentration p-type InGaAs cap layer 107 are formed sequentially on an n-type InP semiconductor substrate 101. It is machined into a broad area laser of a ridge waveguide laser structure and and active layer before depositing a silicon oxide 108 and a planarized polyimide and forming upper and lower electrodes 110, 111. The quantum-well layer is brought into undoped state of an intrinsic carrier concentration of 1×10<17> cm<-3> or less, and a barrier layer is composed of a semiconductor layer of negative or positive conductivity type having a carrier concentration of 1×10<17> cm<-3> or above. According to the structure, threshold level can be lowered.
|
