Method of fabricating a semiconductor laser

DETAILED DESCRIPTION An object of the present invention is to provide a low-threshold and high-output semiconductor laser by improving the processing precision of a ridge structure and suppressing current spreading in the transverse direction.
Other objects and advantages of the invention will become apparent from the detailed description that follows.
The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the scope of the invention will be apparent to those of skill in the art from the detailed description.
According to a first aspect of the present invention, in a method of fabricating a semiconductor laser, a selective growth mask having a stripe-shaped opening in a <011> direction is formed on a {100} surface of a first conductivity type substrate, and a double-heterojunction structure including a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer is formed on the {100} surface of the substrate using the selective growth mask, thereby forming a stripe-shaped ridge including the active layer and the first conductivity type lower cladding layer which are covered with the second conductivity type upper cladding layer, which stripe-shaped ridge has an ordinary mesa-shaped cross-section in a direction perpendicular to the stripe direction and a symmetrical hexagonal cross-section in the stripe direction.
Therefore, the selective etching process for forming the ridge in the conventional method can be dispensed with, whereby variation in the processing precision of the ridge due to the etching process is reduced, and the formation of the ridge is facilitated.
Further, the second conductivity type cladding layer and the active layer grown on the side surfaces of the first conductivity type cladding layer are thin and have low dopant incorporating efficiencies, so that regions of the first conductivity type cladding layer at the side surfaces of the ridge have high resistivity