| 摘要 |
PURPOSE:To do P-type diffusion with excellent controllability from a diffusion source separated from an emitting region to a photowave guide region excluding an element edge and its vicinity by performing the diffusion of impurities to an active layer through a ridge. CONSTITUTION:Each layer is grown on a substrate in order from a lower clad layer 2 to the second upper clad layer 5 of P-type AlGaAs, and further an n-type GaAs cap layer 21 is grown. After Zn is diffused to the cap layer 21, an Si2N4 insulating film is made on the whole of an element surface, and a stripe-shaped insulating film 22 covering both ends of the element in the direction of resonator length is made. Subsequently, with this as an etching mask, it is etched to the level that the second upper clad layer remains little so as to form a ridge. When drive in diffusion of Zn is done through the ridge 23, a low concentration P-type region 12 reaches an active layer 3. Next, an n-type GaAs current checking layer 6 is grown until the ridge 23 is buried. Since a strip-shaped insulating film 22 exists on the ridge 23, selective growth is done, and the wafer is flattened. |
