| 摘要 |
PURPOSE:To stabilize an output, and to improve reproducibility by forming a semiconductor laser having buried type double hetero-structure and a photodetector on the same substrate and detecting laser beams from the semiconductor laser by the photodetector. CONSTITUTION:A P type CaAlAs layer 22 and three layers or more of two kinds of compound semiconductor thin-films having different forbidden band width are laminated on a substrate 21, and quantum well type structure is used as an active layer 24. An N type GaAlAs layer 23 having forbidden band width larger than that of semiconductors is shaped as an upper clad layer, thus forming double hetero-junction structure. An N type GaAs layer 25 as an uppermost layer is etched by utilizing a mask 26 for diffusing an impurity, and the P type impurity is diffused. The two semiconductors constituting a quantum well type are alloyed in an impurity diffusion region in the active layer 24, forbidden band width is made larger than a light-emitting region in the lower section of the N type GaAs layer 25 and an optical waveguide, and a refractive index is reduced. The performance of a laser is improved, and the yield of products is enhanced largely. |
