Semiconductor laser element, method for manufacturing same, and semiconductor laser device
Provided here are: semiconductor layers comprised of an n-type cladding layer formed on a surface of an n-type GaAs substrate, active layers formed on surfaces of the n-type cladding layer, p-type cladding layers formed on surfaces of the active layers, and p-type contact layers formed on surfaces of the p-type cladding layers, the p-type cladding layers and the p-type contact layers being formed to have a ridges; insulating films covering surfaces of the semiconductor layers but having openings on surfaces of the p-type contact layer; and conductive layers connected to the p-type contact layers through the openings, the conductive layers being formed on surfaces of the insulating films to cover planar portions provided in the semiconductor layers adjacently to the ridges; wherein, together with the conductive layers, convex sidewalls are provided to be placed over portions of the planar portions at their sides nearer to the ridges.
1. A semiconductor laser element which is bonded to a sub-mount in a junction-down manner, comprising:
semiconductor layers which are comprised of a first cladding layer formed on a surface of a semiconductor substrate; an active layer formed on a surface of the first cladding layer; a second cladding layer formed on a surface of the active layer; and a contact layer formed on a surface of the second cladding layer; said second cladding layer and said contact layer being formed to have a ridge portion;
an insulating film which covers a surface of the semiconductor layers but has an opening on a surface of the contact layer;
an electrically-conductive layer which is connected to the contact layer through the opening, said electrically-conductive layer being formed on a surface of the insulating film so as to cover a planar portion which is provided in the semiconductor layers adjacently to the ridge portion, the planar portion having a first side and a second side opposite to the first side, a first distance from the ridge portion to the first side being less than a second distance from the ridge portion to the second side; and
a convex part as a sidewall, which is formed over a portion of the planar portion at the first side, so as to surround a solder;
wherein the convex part is configured to retain a spread area of the solder within a non-light emitting region; and
wherein the convex part and the planar portion are bonded to an electrode on the sub-mount through the solder.
2. The semiconductor laser element of claim 1 , wherein the convex part is formed into a C-shape.
3. The semiconductor laser element of claim 1 , wherein the convex part is formed into a comb shape.
4. The semiconductor laser element of claim 1 , wherein a wall depth of the convex part is varied when viewed from a plan view direction.
5. The semiconductor laser element of claim 1 , wherein the convex part is formed as a part of the electrically-conductive layer.
6. The semiconductor laser element of claim 1 , wherein the convex part is formed as a part of the insulating film and its surface is covered with the electrically-conductive layer.
7. The semiconductor laser element of claim 1 , wherein the convex part is formed as a part of the semiconductor layers and is covered with the insulating film and the electrically-conductive layer.
8. A manufacturing method of a semiconductor laser element, comprising:
a step of forming an insulating film covering a surface of semiconductor layers which are comprised of a first cladding layer formed on a surface of a semiconductor substrate; an active layer formed on a surface of the first cladding layer; a second cladding layer formed on a surface of the active layer; and a contact layer formed on a surface of the second cladding layer; said second cladding layer and said contact layer being formed to have a ridge portion, and said insulating film having an opening on a surface of the contact layer;
a step of forming an underlying electrode separately as a first underlying electrode and a second underlying electrode, respectively, on a surface of the insulating film and on surfaces of the contact layer and the insulating film; said first underlying electrode having a plan view shape corresponding to a sidewall which is provided over a planar portion provided in the semiconductor layers adjacently to the ridge portion, at a first side of the planar portion; and said second underlying electrode being connected to the contact layer through the opening, surrounding the first underlying electrode, and covering a surface of the insulating film under which the planar portion is covered; and
a step of plating the first underlying electrode and the second underlying electrode in such a manner that a current value of a current fed to the first underlying electrode is set larger than a current value of a current fed to the second underlying electrode,
wherein the planar portion includes the first side and a second side opposite to the first side, a first distance from the ridge portion to the first side being less than a second distance from the ridge portion to the second side.
9. A semiconductor laser device in which the semiconductor laser element of claim 1 is bonded to an electrode provided on a surface of a sub-mount, through a solder and by way of a portion of the electrically-conductive layer corresponding to the planar portion in the semiconductor laser element and an electrically-conductive layer as a wall surface of the sidewall placed on its side opposite to the ridge portion-side.
10. A semiconductor laser device in which the semiconductor laser element of claim 2 is bonded to an electrode provided on a surface of a sub-mount, through a solder and by way of a portion of the electrically-conductive layer corresponding to the planar portion in the semiconductor laser element and an electrically-conductive layer as a wall surface of the sidewall placed on its side opposite to the ridge portion-side.
11. A semiconductor laser device in which the semiconductor laser element of claim 3 is bonded to an electrode provided on a surface of a sub-mount, through a solder and by way of a portion of the electrically-conductive layer corresponding to the planar portion in the semiconductor laser element and an electrically-conductive layer as a wall surface of the sidewall placed on its side opposite to the ridge portion-side.
12. A semiconductor laser device in which the semiconductor laser element of claim 4 is bonded to an electrode provided on a surface of a sub-mount, through a solder and by way of a portion of the electrically-conductive layer corresponding to the planar portion in the semiconductor laser element and an electrically-conductive layer as a wall surface of the sidewall placed on its side opposite to the ridge portion-side.
13. A semiconductor laser device in which the semiconductor laser element of claim 5 is bonded to an electrode provided on a surface of a sub-mount, through a solder and by way of a portion of the electrically-conductive layer corresponding to the planar portion in the semiconductor laser element and an electrically-conductive layer as a wall surface of the sidewall placed on its side opposite to the ridge portion-side.
14. A semiconductor laser device in which the semiconductor laser element of claim 6 is bonded to an electrode provided on a surface of a sub-mount, through a solder and by way of a portion of the electrically-conductive layer corresponding to the planar portion in the semiconductor laser element and an electrically-conductive layer as a wall surface of the sidewall placed on its side opposite to the ridge portion-side.
15. A semiconductor laser device in which the semiconductor laser element of claim 7 is bonded to an electrode provided on a surface of a sub-mount, through a solder and by way of a portion of the electrically-conductive layer corresponding to the planar portion in the semiconductor laser element and an electrically-conductive layer as a wall surface of the sidewall placed on its side opposite to the ridge portion-side.