JP2736173B2 - Method for manufacturing semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high-power semiconductor laser.

[0002]

2. Description of the Related Art Semiconductor lasers are widely used as light sources for optical disk devices, laser printers and the like. In this case, in order to improve the performance of the optical disk device and the laser printer device, a high output and high reliability of the semiconductor laser are required. A semiconductor laser using an AlGaAs-based material can provide a high output of 30 mW to 40 mW, and is currently used in various devices. However, when the semiconductor laser is operated at a higher output, the end face of the resonator is deteriorated.
This is because non-radiative recombination occurs at the light emitting end face via a surface level, and heat is locally generated. When the end face temperature rises, the heat generated reduces the forbidden band width of the end face part, increases light absorption, and non-emission recombination occurs due to carriers generated by the light absorption through the surface state. Rise. When this process is repeated, the end surfaces are melted and deteriorated. As a way to improve this,
Various organizations have proposed a structure for growing a semiconductor crystal having a larger band gap than the active layer of the laser on the emission end face. An example is an edge growth window type laser. The internal semiconductor laser has a laminated structure including a GaAs active layer or an AlGaAs active layer formed on a GaAs substrate by a known growth method such as a liquid phase growth method or a vapor phase growth method. VSIS laser (V-channeled Substra
te Inner Stripe Laser: Appl. Phys. Lett. , 40,
372 (1982)) (FIG. 14). As a window layer regrowth method, a cavity facet is formed on a semiconductor laser wafer, and an MO
On the susceptor of a CVD apparatus, a laminated structure growth surface side up, and set to the substrate side downward, the resonator on the end face, the active layer (Al _x Ga _1-x As layer) of forbidden band width than A large non-doped Al _z Ga _{1 -z} As layer (z> x) is regrown to produce an end face regrowth window laser.

[0003]

As shown in FIG.
Set on the susceptor in the upward stacked structure growth surface side of the substrate side of the regrown wafer downwards, by the MOCVD method, the window layer on the cavity end face (110) plane 107 (Al _z G
When the a _{1 -z} As layer) 120 is regrown, a window layer (laminated structure growth ) on the laminated structure growth surface (001) surface 108 is grown together with the intended growth on the cavity facet (110) surface 107.
Since the growth of 122 is performed, the two window layers 1 are formed.
Abnormal growth 123 containing many defects occurs at the corner between the cavity facet where the growth of 20 and 122 overlap and the growth surface of the laminated structure. Therefore, as shown in FIGS. 15 and 16, an end face regrowth window laser in which the active layer position on the resonator facet corresponds to the abnormal growth region 123 of the window layer can be obtained. In such a semiconductor laser, scattering loss, disturbance of the transverse mode, and the like occur with respect to the emitted light. In addition, in the device fabrication, a non-dove Al is also provided on the (001) plane of the laminated structure growth surface.
Since _z Ga _1-z As layer is grown, it is necessary to remove this before electrode attachment, without taking _Al z _{Ga 1-z} As layer growing on the cavity end face (110) surface To
Al _z Ga growing on the stacked growth surface 108
_A complicated process is required to remove the _1-z As layer.

[0004]

According to a first aspect of the present invention, there is provided:
Method for manufacturing semiconductor laser device includes active layer on substrate
A semiconductor laser with a laminated structure is used as the internal structure.
A semiconductor layer with a larger forbidden band width than the active layer
A semiconductor laser with a structure formed as a window layer by vapor phase epitaxy.
A method of manufacturing a laser element,
Fixation for fixing susceptor or laser bar of the vapor phase growth apparatus
Of growing the semiconductor layer to be the window layer by bringing it into close contact with the tool
And after taking out from the vapor phase growth apparatus, the laminated structure growth table
Occurs at the corner between the opposite surface and the end surface of the co-plate
Removing the abnormally grown portion.
Things. Manufacturing method of the semiconductor laser of the present invention described above.
Indicates that AlGa having a larger forbidden band width than the active layer is formed on the end face of the resonator.
An edge-grown window-type laser that grows an As semiconductor layer and uses it as a window layer
The growth surface of the multilayer structure is
The window layer is formed in close contact with the
By extending the length, the susceptor is closely
And the window layer 122 does not grow.
Window layer 120 growing on the surface and window layer 1 growing on the substrate surface
21 only grows in both layers. These two layers overlap
At the corner of the substrate, very little abnormal growth 123 occurs,
Since the cavity facet with the active layer is farther from this position,
It is not affected by the abnormal growth,
3 including the step of removing
The morphology of the window layer growing on the end face of the vessel
Can be Further, when the susceptor is grown on the window layer using the susceptor as a growth suppressor, the susceptor is brought into close contact with the laminated structure growth surface, with the laminated structure growth surface side facing downward and the substrate side facing upward, and the susceptor is used as a growth suppressor. Conversely, A on the substrate side surface
Although l z _Ga 1-z _As layer is to grow, as compared to the multilayer structure including an active layer, since the substrate is very thick, Al _{z Ga} 1-z which occurs at the corners of the substrate surface and the end face The abnormal growth region of As does not reach the position of the active layer.
Also, _Al z _{Ga 1-z} As layer removal grown on the substrate surface can be easily carried out by polishing or the like (Fig. 2,
3).

[0005]

Next, a first embodiment of the present invention will be described.

FIG. 1 shows an embodiment of a semiconductor laser device obtained by the manufacturing method of the present invention. In this embodiment, VSIS
The step of regrowing the window layer on the cavity facet using the laser as the internal structure will be described. The point that the VSIS laser has an internal structure is the same as that shown in the conventional example.
FIG. 14 shows the structure of the laser. First, the formation of a VSIS laser, which is an internal stripe laser, will be briefly described, and then a manufacturing method relating to window layer regrowth of the present invention will be described. LPE on p-GaAs substrate 100
An n-GaAs current blocking layer 101 is grown by a (Liquid Phase Epitaxy) method, and a striped V-shaped groove 102 reaching the substrate 100 is formed by photolithography and chemical etching. Next, p-Al ₀ .45 Ga ₀ .55 by the LPE method
The p-Al ₀ .15 Ga _{0 .85} As active layer 104 is grown so as to fill the As cladding layer 103 and the V groove 102 flat.
_{-Al 0 · 45 Ga 0 · 55} As cladding layer 105, n-GaA
The s-contact layer 106 is sequentially grown. Thus, a VSIS laser having an internal structure is manufactured (FIG. 14).

Next, a method for regrowing a window layer according to the present invention will be described. The VSIS laser wafer as an internal structure, to form a resonator facet 107 by cleavage method, by metal organic chemical vapor deposition (MOCVD) on its end face, the carrier concentration 10 ¹⁷ cm ^-3 or less of a high-resistance Al _{0 · 5} Ga _{0 ·} 5 As layer 12
Grow 0. At this time, in the present invention, as shown in FIG.
On the susceptor of the MOCVD device, the laminated structure growth surface side is set downward and in close contact with the susceptor, and the window layer is regrown. On the growth surface of the laminated structure, the window layer does not grow because it is in close contact with the susceptor.
Only the layer 20 and the layer 121 growing on the substrate surface are grown. At the corner of the substrate where these two layers overlap, abnormal growth 123 in which many defects occur occurs. However, since the end face of the cavity where the active layer is located is away from this position, it is not affected by the abnormal growth and this active layer is not affected. The surface morphology of the regrown window layer on the upper cavity facet is better. After the window layer is regrown by the MOCVD method, the window layer Al ₀ .5 G grown on the substrate
the removal of a _{0 ·} 5 As. This is performed by polishing or chemical etching (FIG. 3). Since the surface on the side of the growth surface of the double hetero layer was in close contact with the susceptor, the window layer did not grow, so that the removal step was unnecessary. (Or sulfuric acid-based etchant (H ₂ SO ₄ : H ₂
O ₂ : H ₂ O = 5: 10: 100). Then, the p-GaAs substrate 100 side and n-G
A p-type electrode 140 and an n-type electrode 141 are formed on the surface on the side of the aAs contact layer 106. On the window layer (Al ₀ .5 Ga ₀ .5 As layer) grown on the end face of the resonator, end face protective films 142 and 142 ′ such as Al ₂ O ₃ are formed to control the end face reflectivity (FIG. 4). .

By improving the window layer growth method as described above, the crystallinity of the window layer at the emission end face having the oscillation region is improved and the mirror surface becomes mirror-like. The disturbance of the transverse mode caused by the above was eliminated. FFP (far-field) by the conventional window layer growth method
pattern) horizontal mode and FF in the window layer growth method of this embodiment
The P horizontal mode is shown in FIGS.

FIG. 7 shows a second embodiment of the present invention. The window layer 120 growing on the resonator end face with the active layer is provided by placing the growth preventing jig 131 on the stacked structure growth surface to suppress the growth of the semiconductor layer serving as the window layer on the stacked structure growth surface. Has good surface morphology.

FIGS. 8 to 10 show a third embodiment. Bar-shaped wafer (laser bar) with cleaved surface and long cavity length
109 is fixed by a fixing jig 132 to grow a window layer.
The growth surface of the laminated structure is in close contact with the fixing jig, or
The window layer is prevented from growing on the growth surface of the laminated structure by being in close contact with the growth preventing jig 131. The materials for the fixing jig and the growth preventing jig are carbon, PBN, quartz, GaAs,
Any of Si and InP may be used, and some combination thereof may be used.

FIG. 11 shows a fourth embodiment. By overlapping a plurality of laser bars 109, the growth of the window layer on the growth surface of the laminated structure is suppressed. FIG. 11 shows a method in which the laser bar 109 is directly placed on the susceptor 130, but may be attached to a fixing jig.

FIG. 12 shows a fifth embodiment. In the above-described embodiments, the growth preventing jig, the fixing jig, and the susceptor are brought into close contact with the laminated structure growth surface. However, as shown in FIG. Even if they are not in close contact, if they are close enough, MOCV
In the method D, it becomes difficult for the source gas to flow on the growth surface of the laminated structure. Therefore, the growth of the window layer 122 on the growth surface of the laminated structure
As compared with the growth of the window layer 120 on the end face of the resonator, the growth is sufficiently small, and the abnormal growth 123 at the corners is reduced. Therefore, the abnormal growth does not reach the active layer, and the morphology on the end face of the resonator having the active layer becomes good.

FIG. 13 shows a sixth embodiment. A growth preventing film such as SiO ₂ 133, Al ₂ O ₃ , or SiN is formed on the growth surface of the laminated structure, so that the growth of the semiconductor layer serving as the window layer on the growth surface of the laminated structure is eliminated. Good morphology. After the growth of the window layer, the growth-preventing film is selectively removed.
A high-power semiconductor laser without P disturbance can be obtained.

In the above embodiment, VSI is used as the internal structure.
Although the S laser has been described, similar effects can be obtained with other resonator type lasers. Although the case where the active layer has a double hetero structure has been described, other structures such as a quantum well structure may be used. A dry etching method other than the cleavage method and a chemical etching method may be used as a method for forming the cavity end face. The semiconductor laser according to the present embodiment shows a case in which an AlGaAs semiconductor layer having a larger forbidden band width than the active layer is grown on the cavity end face of the laminated structure including the GaAs or AlGaAs active layer.
Other materials such as 1P-based and InGaAsP-based materials may be used. In addition, if the semiconductor layer grown on the cavity facet is also a material having a larger forbidden band width than the active layer, an InGaAlP-based material may be used.
Another material such as InGaAsP may be used. Further, as the regrowth method on the cavity end face, other methods such as a vapor growth method other than the MOCVD method, such as the MBE method, the ALE method, and the MOMBE method may be used.

[0015]

As described above, according to the first aspect of the present invention,
According to the method of manufacturing a semiconductor laser device, an active layer is formed on a substrate.
Semiconductor laser with a laminated structure containing
The end face of the resonator has a half band with a larger forbidden band width than the active layer.
A structure in which a conductor layer is formed as a window layer by vapor deposition
A method for manufacturing a semiconductor laser device, comprising:
A susceptor or a laser bar of the vapor phase growth apparatus
Growing the semiconductor layer to be the window layer by closely adhering to the fixing jig
And removing the laminated structure from the vapor-phase growth apparatus.
Developed at the corner between the surface opposite to the growth surface and the end face of the co-plate.
Removing the abnormally growing portion that occurs.
It is assumed that. Therefore, the semiconductor laser device of the present invention
The manufacturing method of the method has a larger forbidden band width than the active layer on the cavity end face.
Face growth window using a new AlGaAs semiconductor layer as a window layer
Type laser, wherein the growth surface of the laminated structure is formed by the vapor phase growth.
Closely contact the susceptor of the device or the jig for fixing the laser bar.
By growing the window layer by sputtering,
The window layer 122 does not grow due to the close contact with the septa.
The window layer 120 grown on the cavity end face and the substrate surface.
Only the long layer of the window layer 121 is grown. These two layers
Are slightly abnormal growth 123 at the corner of the substrate where
Occurs, but the cavity facet with the active layer is separated from this position.
Is not affected by abnormal growth.
By including the step of removing the normal growth portion 123, the morphology of the window layer grown on the resonator end face having the active layer can be improved. From this, it is possible to eliminate scattering loss, transverse mode disturbance, and the like with respect to light emitted through the window layer, and obtain a high-output semiconductor laser having a well-shaped beam and high oscillation efficiency.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of an edge window type semiconductor laser device of the present invention.

FIG. 2 is a sectional view in the direction of a resonator in a V-groove when a window layer is grown according to the first embodiment.

FIG. 3 is a cross-sectional view in the direction of a resonator in a V-groove in an element forming step of the first embodiment.

FIG. 4 is a sectional view in the direction of the resonator in the V-groove of the device manufactured according to the first embodiment.

FIG. 5 is an FFP horizontal mode diagram of a laser using a conventional window layer growth layer.

FIG. 6 is an FFP horizontal mode diagram of a laser using a growth layer according to the present embodiment.

FIG. 7 is a sectional view of the window layer regrown wafer according to the second embodiment, taken in the direction of the resonator in the V-groove.

FIG. 8 is a perspective view of a jig for fixing a laser bar according to a third embodiment.

FIG. 9 is a cross-sectional view of the window layer regrown wafer according to the third embodiment, taken in the direction of the resonator in the V-groove.

FIG. 10 is an overall view of a jig for fixing a laser bar.

FIG. 11 is a sectional view in the V-groove resonator direction at the time of window layer regrowth according to the fourth embodiment.

FIG. 12 is a sectional view in the direction of the resonator in the V-groove at the time of window layer regrowth according to the fifth embodiment.

FIG. 13 is a sectional view in the direction of the resonator in the V-groove at the time of window layer regrowth according to the sixth embodiment.

FIG. 14 is a perspective view of a VSIS laser wafer.

FIG. 15 is a cross-sectional view in the direction of a resonator in a V-groove when a window layer is grown in a conventional example.

FIG. 16 is a perspective view of an end face window type semiconductor laser device by a conventional growth method.

[Explanation of symbols]

100 p-GaAs substrate 101 current blocking layer n-GaAs 102 V groove 103 cladding layer _{p-Al y Ga 1-y} As (y =
0.45) 104 active layer p-Al _x Ga _{1 -x} As (x =
0.15) 105 clad layer _{p-Al y Ga 1-y} As (y =
0.45) 106 contact layer n-GaAs 107 resonator end face 108 stacked structure growth face 109 laser bar 110 stacked structure section 120 window layer (grown on resonator end face) Al _z Ga _1-z A
s (z = 0.50) 121 Window layer (grown on substrate) Al _z Ga _{1 -z} A
s (z = 0.50) 122 Window layer (grown on the growth surface of the laminated structure) Al _z Ga _{1 -z} A
s (z = 0.50) 123 Window layer (corner growth abnormal region) Al _z Ga _{1 -z} A
s (z = 0.50) 130 susceptor 131 growth preventing jig 132 laser bar fixing jig 133 S _i O ₂ film 140 p-type electrode 141 n-type electrode 142 and 142 'the end face protective film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadayoshi Takeoka 22-22 Nagaikecho, Abeno-ku, Osaka City Inside Sharpe Corporation (72) Inventor Saburo Yamamoto 22-22 Nagaikecho, Abeno-ku, Osaka City Inside Sharpe Corporation ( 56) References JP-A-1-227485 (JP, A) JP-A-54-126488 (JP, A) JP-A-55-115386 (JP, A) JP-A-60-140779 (JP, A) Showa 61-154088 (JP, A) Actually open Showa 57-6267 (JP, U)

Claims (1)

(57) [Claims] 1. A semiconductor laser having a laminated structure including an active layer formed on a substrate as an internal structure, and a semiconductor layer having a larger forbidden band width than an active layer is formed as a window layer on a cavity end face by a vapor phase growth method. In the method for manufacturing a semiconductor laser device having a structure to be formed, the stacked structure growth surface is brought into close contact with a susceptor or a laser bar fixing jig of the vapor phase growth apparatus,
A step of growing a semiconductor layer serving as a window layer, and a step of removing an abnormally grown portion generated at a corner between the opposite surface of the laminated structure growth surface and the end face of the co-plate after removal from the vapor phase growth apparatus, And a method for manufacturing a semiconductor laser device.