| 摘要 |
PURPOSE:To eliminate the need for establishing difficult process conditions and obtain a semiconductor laser that is favorably reproducible by forming a current bottleneck layer like a stripe in the direction of optical axis and also in the position corresponding to an external waveguide layer at both sides of an active region on a substrate. CONSTITUTION:Recessed grooves 1b and 1c are formed by photolithography on an upper plane of a p-InP substrate 1. In such a case, widths of the recessed grooves 1b and 1c are formed so that they are equal to that of an external waveguide layer 4 or slightly larger than that of the layer 4 and there is a somewhat difference between both widths of the grooves and the layer. Further, their positions are so correspondent to a position of the waveguide layer 4 in a distributed reflection region that the grooves are formed at both sides of an active region where a part of the active region used as a current path is excluded. Then N-InGaAsP current bottleneck layers 15 perform an epitaxial growth on the substrate 1. In such a case, a width between 1b and 1c is so narrow that it is filled with its growth in a short time and its upper plane becomes flat. This approach makes it possible to form simply the current bottleneck layers that are favorably reproducible without establishing difficult process conditions. |
