Patent ID: 7463662

Claim:
An optical semiconductor device comprising: a semiconductor substrate of a first conductivity type, having a first face, and a second face that is a face on a side of the semiconductor substrate, opposite from the first face; a first cladding layer made up of a semiconductor layer of the first conductivity type and formed over the first face of the semiconductor substrate; an active layer formed on top of the first cladding layer; a second cladding layer made up of a semiconductor layer of a second conductivity type and formed on top of the active layer; a contact layer made up of a semiconductor layer of the second conductivity type and formed over the second cladding layer; an insulating layer covering the second cladding layer to expose the contact layer; a barrier metal layer made of metal contact layer and connecting to the exposed contact layer; a first electrode comprising a Au plating layer and formed on top of the barrier metal layer; and a second electrode formed on the second face of the semiconductor substrate, wherein the two separation grooves are formed in layers and comprise the second cladding layer and contact layer over the active layer, whereby a ridge in a stripe-like shape between two separation grooves is formed, wherein a side part of the contact layer comprises an extremity, wherein the extremity of the side part of the contact layer overhangs the separation groove, underlies the insulating film, and comprises a tilted face undergoing gradual decrease in thickness toward the two separation grooves, wherein the first tilted angle formed between the top face and the first tilted face and the second angle of the contact layer between the top face and the second tilted face are each defined as an obtuse angle, wherein the barrier metal layer is further formed to directly cover the contact layer of the ridge, and is formed directly on the insulating film, and wherein the insulating layer overhangs the separation groove.