Semiconductor laser device and method of fabricating the same

Details Semiconductor laser device and method of fabricating the same Semiconductor laser device and method of fabricating the same

2002-09-05

2004-08-03

Wong, Don (Department: 2828)

Coherent light generators

Particular temperature control

Heat sink

Reexamination Certificate

active

06771676

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor laser device and a method of fabricating the same, and more particularly, it relates to a semiconductor laser device formed by mounting a semiconductor laser element on a base in a junction-down system and a method of fabricating the same.
2. Description of the Background Art
A semiconductor laser device formed by mounting a semiconductor laser element on a submount (base) in a junction-down system is known in general. The junction-down system is a method of fixing a surface of the semiconductor laser element closer to an emission layer to the submount.
FIG. 17
is a sectional view showing a semiconductor laser element
100
having a plurality of ridge portions according to first prior art taken along a direction perpendicular to a cavity. The structure of the semiconductor laser element
100
having a plurality of ridge portions according to the first prior art is described with reference to FIG.
17
.
In the semiconductor laser element
100
having a plurality of ridge portions according to the first prior art, an n-type buffer layer
102
of n-type GaInP having a thickness of about 0.3 &mgr;m, an n-type cladding layer
103
of n-type AlGaInP having a thickness of about 2 &mgr;m, a multiple quantum well (MQW) emission layer
104
of GaInP/AlGaInP and a p-type first cladding layer
105
of p-type AlGaInP having a thickness of about 0.3 &mgr;m are successively formed on an n-type GaAs substrate
101
, as shown in FIG.
17
.
A mesa (trapezoidal) ridge portion constituted by a p-type second cladding layer
106
of p-type AlGaInP having a thickness of about 1.2 &mgr;m and a p-type contact layer
107
of p-type GaInP having a thickness of about 0.1 &mgr;m is formed on the central portion of the p-type first cladding layer
105
. This ridge portion is in the form of a stripe having a bottom portion of about 2.5 &mgr;m in width. Dummy ridge portions similar in structure to the ridge portion are formed to hold the ridge portion located at the center therebetween at prescribed intervals.
An n-type optical confinement layer
108
of n-type AlInP having a thickness of about 0.3 &mgr;m and an n-type current blocking layer
109
of n-type GaAs having a thickness of about 0.5 &mgr;m are formed to cover the upper surface of the p-type first cladding layer
105
and the upper and side surfaces of the dummy ridge portions located on the right and left sides while exposing only the upper surface of the central ridge portion. Therefore, no current flows to the dummy ridge portions. A p-type cap layer
110
of p-type GaAs having a thickness of about 3 &mgr;m is formed to cover the upper surface of the central ridge portion and the overall upper surface of the n-type current blocking layer
109
.
A p-side electrode
111
consisting of a multilayer film of a Cr layer having a thickness of about 0.1 &mgr;m and an Au layer having a thickness of about 3 &mgr;m is formed on the p-type cap layer
110
. The p-side electrode
111
is formed to have a shape comprising recess portions and projection portions reflecting the shapes of the ridge portion and the dummy ridge portions, while parts of the p-side electrode
111
located on the dummy ridge portions are formed on positions higher than a part of the p-side electrode
111
located on the upper surface of the central ridge portion by the thicknesses of the n-type optical confinement layer
108
and the n-type current blocking layer
109
. An n-side electrode
112
consisting of a multilayer film of an Au—Ge layer having a thickness of about 0.2 &mgr;m, an Ni layer having a thickness of about 0.01 &mgr;m and an Au layer having a thickness of about 0.5 &mgr;m is formed on the back surface of the n-type GaAs substrate
101
.
FIG. 18
is a sectional view showing the semiconductor laser element
100
according to the first prior art shown in
FIG. 17
in a state mounted on a submount
113
in a junction-down system. Referring to
FIG. 18
, the semiconductor laser element
100
according to the first prior art is mounted on the submount (base)
113
set on a stem (not shown) while directing the p-side electrode
111
formed on the surface thereof downward in the junction-down system. A metal film
114
consisting of Ti, Pt and Au is formed on an aluminum nitride layer provided on the upper surface of the submount
113
. A low melting point metal layer
115
of Pb—Sn 60% or Ag—Sn 95% serving as a fusing material is formed on the metal film
114
.
In order to mount the semiconductor laser element
100
on the submount
113
while directing the p-side electrode
111
downward in the junction-down system, the low melting point metal layer
115
serving as the fusing material bonds (welds) projection portions of the p-side electrode
111
to the submount
113
. In this case, voids
116
are formed between recess portions of the p-side electrode
111
and the low melting point metal layer
115
.
FIG. 19
is a sectional view of a semiconductor laser element
120
having a single ridge portion according to second prior art taken along a direction perpendicular to a cavity. The structure of the semiconductor laser element
120
having a single ridge portion according to the second prior art is now described with reference to FIG.
19
.
In the semiconductor laser element
120
having a single ridge portion according to the second prior art, an n-type buffer layer
102
, an n-type cladding layer
103
, an MQW emission layer
104
and a p-type first cladding layer
105
are successively formed on an n-type GaAs substrate
101
, similarly to the semiconductor laser element
100
according to the first prior art shown in FIG.
17
. The thicknesses and compositions of these layers
102
to
105
are similar to those of the semiconductor laser element
100
according to the first prior art shown in FIG.
17
.
A mesa (trapezoidal) ridge portion consisting of a p-type second cladding layer
121
of p-type AlGaInP having a thickness of about 1.2 &mgr;m and a p-type contact layer
122
of p-type GaInP having a thickness of about 0.1 &mgr;m is formed on the p-type first cladding layer
105
. This ridge portion is in the form of a stripe having a bottom portion of about 2.5 &mgr;m in width.
An n-type optical confinement layer
123
of n-type AlInP having a thickness of about 0.3 &mgr;m and an n-type current blocking layer
124
of n-type GaAs having a thickness of about 0.5 &mgr;m are formed to cover the upper surface of the p-type first cladding layer
105
while exposing only the upper surface of the ridge portion. A p-type cap layer
125
of p-type GaAs having a thickness of about 3 &mgr;m is formed to cover the upper surface of the ridge portion and the overall upper surface of the n-type current blocking layer
124
.
A p-side electrode
126
consisting of a multilayer film of a Cr layer having a thickness of about 0.1 &mgr;m and an Au layer having a thickness of about 3 &mgr;m is formed on the p-type cap layer
125
. The p-side electrode
126
is formed to have a shape comprising recess portions and projection portions reflecting the shape of the ridge portion. An n-side electrode
127
consisting of a multilayer film of an Au—Ge layer having a thickness of about 0.2 &mgr;m, an Ni layer having a thickness of about 0.01 &mgr;m and an Au layer having a thickness of about 0.5 &mgr;m is formed on the back surface of the n-type GaAs substrate
101
.
FIG. 20
is a sectional view showing the semiconductor laser element
120
according to the second prior art shown in
FIG. 19
in a state mounted on a submount
113
in the junction-down system. Referring to
FIG. 20
, the semiconductor laser element
120
according to the second prior art is mounted on the submount (base)
113
set on a stem (not shown) while directing the p-side electrode
126
formed on the surface thereof downward in the junction-down system. A metal film
114
consisting of Ti, Pt and Au is formed on an aluminum nitride layer provided on the upper surface of the submount
113
. A low melting point metal layer

Affiliated with

Also associated with

Rating

Semiconductor laser device and method of fabricating the same does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Semiconductor laser device and method of fabricating the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor laser device and method of fabricating the same will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3314286