JP2000068553A - Super luminescent diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SLD reducing the intensity modulation in output beam spectrum following after beam reflection due to the rapid change in equivalent refractive index caused in the boundary between a current implanted region and a not implanted region. SOLUTION: Within a super luminescent diode(SLD), a current implanted end (18) slowly reducing the current implanted amount is provided between a current implanted region (11) sectioned by a current implanting part (14) to an active layer (3) and not implanted region (13) for inserting a transfer region (12). In such a constitution, the current implanted end (18) for avoiding the rapid change in the equivalent refractive index of the waveguide by the active layer (3) is provided, thereby making feasible of reducing the intensity modulation of a spectrum by avoiding the reflection on this end (18).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device used for various optical measurements such as optical communication and optical fiber gyros, and more particularly, to a super luminescent device which outputs a wide spectrum with a large intensity and a small radiation angle. It is about a St diode.

[0002]

2. Description of the Related Art A conventional super luminescent diode (SLD) will be described with reference to FIG. FIG.
FIG. 1 is a view showing the structure of a conventional ridge-type SLD, which is InGaAs / InP having a light emission center wavelength band of 1.3 μm.
FIG. 4 is a diagram showing a structural example of a conventional SLD using a system material.
10A is a schematic view of an SLD having a conventional structure viewed from above the first electrode side, and FIG.
FIG. 10C is a diagram schematically showing a layer structure appearing on the AA ′ section in the figure, and FIG. 10C is a schematic view of the BB section in FIG. In order to obtain this SLD, an n-type conductive InP (1.5 μm thick) first cladding layer 52 and an InGaAsP / InGaAsP MQW are formed on an n-type conductive InP semiconductor substrate 51.
20 active layers 53 (total layer thickness 0.15 μm), p-type conductive InP (2.3 μm layer thickness) second cladding layer 5
4. A double hetero layer structure is formed by sequentially epitaxially growing the p-type conductive InGaAs (layer thickness: 0.6 μm) contact layer 55 by MOVPE. In addition,
The second cladding layer 54 has a thickness of 0.3 μm above the active layer 53.
At m, an etch stop layer (not shown) of InGaAs (layer thickness: 15 nm) is formed. Next, a resist is patterned to form two current constriction grooves 56 for increasing the current density in the active layer 53 and improving the luminous efficiency.

Using this resist as a mask, the InGaAs contact layer 55 in the groove 56 is etched by chemical etching (H ₂ SO ₄ : H ₂ O ₂ : H ₂ O = 1: 1: 40) to remove the resist. After the removal, the second cladding layer 54 of p-InP is chemically etched (HCl: H ₂ O = 1.5: using the contact layer 55 of InGaAs as a mask).
In 1), etching is performed up to an etch stop layer 0.3 μm above the active layer 53.

Thus, a stripe-shaped ridge 60 having a width of 3 μm is formed between the grooves 56. The SiO ₂ dielectric film 57 was 0.4μm deposited by a CVD method on the upper surface of the contact layer 55, to open the window by dry etching a dielectric film of SiO ₂ of the ridge 60.

At this time, the depth of the groove 56 is set so as not to reach the active layer 53 in order to ensure element operation reliability and basic lateral mode operation. The portion where the groove 56 is formed becomes a current injection region 58, and the portion where the groove 56 is not formed becomes a non-injection region 59.

Ti (0.02 μm), Pt (0.05 μm) are formed on the growth surface of the wafer obtained through the above steps.
And Au (0.2 μm) are deposited by electron beam evaporation. The lower portion of the semiconductor substrate 51 has a layer thickness of 1 by mechanical polishing.
Polished to 00 μm, Ti (0.02 μm), Pt
(0.05 μm) and Au (0.2 μm) are deposited by electron beam evaporation.

After these depositions, at a temperature of 410.degree.
Heat treatment for 2 seconds to obtain an alloy, the first electrode 61 and the second electrode 61
Is formed.

This wafer is cleaved along the light emitting end face, and an AR coating 63 of SiO is applied to the light emitting end face. The AR coating 63 has a reflectance of 0.2
%, The current injection region 5 from the rear end face by the non-injection region 59.
The ratio of the optical power returning to 8 is 0.001% or less, so that laser oscillation is suppressed and the operation as an SLD is realized. After these steps, the wafer is sized to a predetermined size (30
(Approximately 0 μm and 400 μm) to obtain chip-shaped elements.

This SLD device has an injection current of 150 m
In A, an optical output of about 4 mw and a full width at half maximum of the optical spectrum of about 20 nm are obtained, and the ripple of the optical spectrum is about 5% due to the effect of the AR coating 63 and the non-injection region 59.

[0010]

SUMMARY OF THE INVENTION Such a conventional SL
In D, in order to suppress laser oscillation, a non-injection region is formed following the current injection region to suppress reflection at the end face of the active layer. Since the electrode and the ridge waveguide are suddenly cut off at this boundary, a sharp difference in injected carrier amount and discontinuity of the waveguide occur at this boundary. As a result, at this boundary, the equivalent refractive index of the current injection region and the non-injection region changes abruptly, and there is a disadvantage that light is reflected and intensity is modulated in the spectrum by the Fabry-Perot mode.

The present invention provides an SLD in which the intensity modulation of the spectrum of the output light due to a sudden change in the equivalent refractive index of the waveguide generated at the boundary between the current injection region and the non-injection region is reduced.

[0012]

A super luminescent diode according to the present invention comprises a semiconductor substrate 1, a first cladding layer 2 formed on the semiconductor substrate, and a super cladding layer 2 formed on the first cladding layer. An active layer 3 having one end as a light emitting end, a second cladding layer 4 formed on the active layer, a contact layer 5 formed on the second cladding layer, and A superimposing device comprising: a current injection portion 14 extending in a stripe shape from the emission end side to the other end side for injecting a current into the active layer; and a current injection region 11 defined by a tip of the current injection portion. In the luminescent diode, a current injection end portion 18 in which the width of the stripe is gradually reduced from the tip of the current injection portion toward the other end is provided, so that the current injection region;
A transition region 12 in which the current to be injected gradually decreases from the current injection region to the non-injection region is formed between the current injection region and the non-injection region 13 where no current is injected.

Further, a superluminescent diode according to the present invention comprises a semiconductor substrate 1, a first cladding layer 2 formed on the semiconductor substrate, and a light-emitting end formed on the first cladding layer. An active layer 3 as an emission end of
A second cladding layer 4 formed on the active layer, a contact layer 5 formed on the second cladding layer, and a stripe shape on the contact layer from the emission end side to the other end side; A current injection portion 14 for injecting a current into the active layer, a current injection region 11 defined by a tip of the current injection portion, and along both sides thereof to form the current injection portion in a stripe shape. In the super luminescent diode provided with the provided ridge-forming grooves 6, 6, a current injection end portion 22 extending in a stripe shape from the tip of the current injection portion to the other end side; A groove end portion 21 is provided along both sides of the end portion, the width of which gradually decreases from the tip of the current injection portion to the other end side, so that the current injection region and the non-injection not injecting current are provided. region Between the 3, the equivalent refractive index toward the non-injection region from said collector inlet region is obtained by forming a transition region 12 gradually increases.

Further, a super luminescent diode according to the present invention comprises a semiconductor substrate 1, a first cladding layer 2 formed on the semiconductor substrate, and a light emitting end formed on the semiconductor substrate and having one end. An active layer 3, a second clad layer 4 formed on the active layer, a contact layer 5 formed on the second clad layer, and another contact layer formed on the contact layer from the emission end side. A current injection portion extending in a stripe shape toward an end to inject a current into the active layer; a current injection region defined by a tip of the current injection portion; and a current injection portion formed in a stripe shape And a ridge-forming groove 6 provided along both sides of the current-injecting portion to extend in a stripe shape from the tip of the current injection portion toward the other end. A current injection end portion 22 and a groove end portion 21-1 provided along both sides of the current injection end portion, the depth of which gradually decreases from the tip of the current injection portion toward the other end side; A transition region 12 in which the equivalent refractive index gradually increases from the current injection region toward the non-injection region is formed between the current injection region and the non-injection region 13 into which no current is injected.

Further, a super luminescent diode according to the present invention comprises a semiconductor substrate 1, a first cladding layer 2 formed on the semiconductor substrate, and a light-emitting end formed on the first cladding layer. An active layer 3 as an emission end of
A second cladding layer 4 formed on the active layer, a contact layer 5 formed on the second cladding layer, and a stripe shape on the contact layer from the emission end side to the other end side; A current injection portion 14 for injecting a current into the active layer, a current injection region 11 defined by a tip of the current injection portion, and both sides thereof for forming the current injection portion in a stripe shape. Current-injecting end portion 18 in which the stripe width gradually decreases from the tip of the current-injecting portion toward the other end side in the superluminescent diode provided with the ridge-forming grooves 6, 6 provided.
And a groove end portion 21 provided along both sides of the current injection end portion, the width of which gradually decreases from the tip of the current injection portion toward the other end side, whereby the current injection region; A transition region 12 in which a current to be injected gradually decreases and an equivalent refractive index gradually increases from the current injection region to the non-injection region is formed between the non-injection region 13 and no current injection. is there.

Further, a superluminescent diode according to the present invention comprises a semiconductor substrate 1, a first cladding layer 2 formed on the semiconductor substrate, and a light-emitting end formed on the first cladding layer. An active layer 3 as an emission end of
A second cladding layer 4 formed on the active layer, a contact layer 5 formed on the second cladding layer, and a stripe shape on the contact layer from the emission end side to the other end side; A current injection portion 14 for injecting a current into the active layer, a current injection region 11 defined by a tip of the current injection portion, and both sides thereof for forming the current injection portion in a stripe shape. Current-injecting end portion 18 in which the stripe width gradually decreases from the tip of the current-injecting portion toward the other end side in the superluminescent diode provided with the ridge-forming grooves 6, 6 provided.
And a groove end 21-1 provided along both sides of the current injection end and gradually decreasing in depth from the tip of the current injection part toward the other end, thereby providing the current injection Between the region and the non-injection region 13 where no current is injected
A transition region 12 is formed from the current injection region to the non-injection region, in which the injected current gradually decreases and the equivalent refractive index gradually increases.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A super luminescent diode (SLD) according to the present invention is provided between a current injection region defined by a current injection portion for injecting current into an active layer and a non-injection region not injected. A transition region was inserted by providing a current injection end where the amount of current injection gradually decreased.

It is possible to prevent the equivalent refractive index of the waveguide portion formed of the active layer from changing abruptly at the tip of the current injection portion, to reduce the reflection on this surface, and to prevent the intensity modulation of the spectrum. it can.

At the current injection end where the amount of current injection gradually decreases, the shape of the electrode or contact layer for current injection gradually narrows from the current injection region to the non-injection region. Further, the width of the ridge forming groove on both sides of the current injection portion is gradually reduced, or the depth of the groove is gradually reduced. Thereby, the equivalent refractive index is gradually increased.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing the configuration of the first embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of an original wafer used in the embodiment of the present invention.

The original wafer shown in FIG. 2 has a layer structure in which the following layers are sequentially grown on an n-InP semiconductor substrate 1 by MOVPE.

First cladding layer 2 of n-InP.

An active layer 3 of InGaAsP.

A second cladding layer 4 of p-InP.

A contact layer 5 of p-InGaAs.

The first embodiment shown in FIG. 1 is formed using the original wafer shown in FIG. In FIG. 1, (a) is a view of the SLD of this embodiment as viewed from above the original wafer, (b) is a view showing a cross section taken along the line AA 'of (a), and (c) is a view of B- of (a).
It is a figure which shows the B 'cross section.

In FIG. 1, 6 is a groove, 7 is a dielectric layer, 8
Is an etch stop layer, 11 is a current injection region, 12 is a transition region, 13 is a non-injection region, 14 is a ridge portion serving as a current injection portion, 15 is a first electrode, 16 is a second electrode, and 17 is an AR coating. , 18 are projections of the contact layer 5 serving as current injection ends, 19 is an etched portion of the contact layer 5, and 20 is the other end.

The groove 6 is dug inward from the side of the AR coating 17 at a depth up to the etch stop layer 8 with the upper and lower central portions of FIG.
4 is formed. In the contact layer 5, of the transition region 12 and the non-implanted region 13 in FIG. 1A, the right contact layer etching portion 19 distinguished by the dotted line is etched, and only the left portion of the dotted line is left. Of the remaining portion of the contact layer 5, the contact layer above the ridge portion 14 is a current injection portion, and the protrusion of the contact layer 5 following the current injection portion has a length of approximately 200 μm. 18). The current injection end portion 18 has a width of approximately 3
μm.

The current injection section 14 and the current injection end 1
The dielectric layer 7 is formed except for the layer 8 and the first
Is formed.

A second electrode 16 is provided below the semiconductor substrate 1, and a current flows between the second electrode 16 and the first electrode 15. The region where the current injection portion 14 exists is the current injection region 11, and the region where the current injection end 18 exists is the transition region 1.
2. The region into which no current is injected is the non-injection region 13.

The portion of the active layer 3 corresponding to the lower side of the ridge portion 14 sandwiched between the grooves 6, 6 has a high refractive index portion (3. 1) surrounded by a low refractive index (about 3.1). .5)
And is called a waveguide portion.

Next, the operation will be described.

When a current flows between the first electrode 15 and the second electrode 16, the current is injected into the active layer 3 via the current injection part 14 and the current injection end part 18 to emit light.
At this time, the equivalent refractive index of the active layer 3 is gradually changed in the transition region 12 because the current injection end portion 18 is provided with a gradually narrower width.

For this reason, light generated in the active layer 3 is scattered from the current injection region 11 to the non-injection region 13 without being reflected. Obtainable.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing the configuration of the second embodiment of the present invention.
Same as (b). The second embodiment is similar to the first embodiment shown in FIG.
The shapes of the current injection end portion 18 and the groove 6 are different from those of the embodiment of FIG.

That is, the second embodiment shown in FIG.
The groove 6 shown in FIG. 1 extends rightward in the drawing while gradually decreasing in width from both sides of the ridge portion 14, and a groove end (hereinafter, also referred to as a groove protrusion) 21 is formed on the ridge portion 14. The protrusion 22 is formed in a substantially rectangular shape.

The etched portion 19-1 of the contact layer 5 is on the right side, which is divided by the dotted line in FIG. 3, and is etched leaving the protrusion 21 of the groove and the protrusion 22 of the ridge portion.

In the second embodiment, the current injection is performed through the contact layer 5 on the ridge portion 14 and the contact layer 5 on the protrusion 22 of the ridge portion. Transition area 1
In No. 2, since the protrusion 21 of the groove having a width of about 10 μm and a length of 200 μm on the side of the current injection region 11 is gradually narrowed toward the non-injection region, the equivalent refractive index of the waveguide portion is gradually reduced. It changes to the equivalent refractive index of the injection region 13.

In this case, it is considered that light senses a change in the equivalent refractive index in the latter half of the transition region 12. Therefore, the above dimensions vary depending on design conditions.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing the configuration of the third embodiment of the present invention.
Same as (b). The third embodiment is similar to the first embodiment shown in FIG.
The shapes of the current injection end portion 18 and the groove 6 are different from those of the embodiment of FIG. FIG. 4B is a diagram showing a cross section taken along line CC ′ of FIG.

That is, the third embodiment shown in FIG.
As shown in FIG. 4, the width gradually increases from both sides of the ridge portion 14, and while the depth decreases, the protrusion 21-1 of the groove extending rightward in the drawing substantially replaces the protrusion 22 of the ridge portion. It is formed in a rectangular shape. In FIG. 4B, the depth of the protrusion 21-1 of this groove is 0.2 to 0.3 μm on the side of the current injection region 11 as represented by the distance between the active layer 3 and the dielectric layer 7; The region 13 has a length of about 2 to 3 μm, and the transition region 12 has a length of about 200 μm.

As in the second embodiment, the etched portion 19-1 of the contact layer 5 is on the right side, which is divided by the dotted line in FIG. 4, and is etched leaving the groove projection 21-1 and the ridge projection 22. Have been. In the third embodiment, the current injection is performed through the contact layer 5 on the ridge portion 14 and the contact layer 5 on the protrusion 22 of the ridge portion. In the transition region 12, since the protrusion 21-1 of the groove gradually becomes shallow, the equivalent refractive index of the waveguide portion gradually changes,
It approaches the equivalent refractive index of the non-injection region 13. In this case, it is considered that the light perceives as a change in the equivalent refractive index about 1 μm immediately after entering the transition region 12. Therefore, the above dimensions vary depending on design conditions.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram showing the configuration of the fourth embodiment of the present invention.
Same as (b). The fourth embodiment is similar to the first embodiment shown in FIG.
The shape of the groove 6 is different from that of the embodiment.

That is, the fourth embodiment shown in FIG.
At the tip of the groove 6 shown in FIG. 1, a protrusion 21 of a groove extending rightward in the drawing while gradually narrowing from both sides of the ridge portion 14 is formed.
Are formed in a substantially rectangular shape.

The etching portion 19 of the contact layer 5 is
As in the example of FIG. 5, the right side is divided by the dotted line in FIG.
The right side of the current injection region 11 is etched except for the protrusion 18 of the contact layer. In the fourth embodiment, the current injection is performed through the contact layer 5 on the ridge portion 14 and the protrusion 18 of the contact layer, but since the protrusion 18 of the contact layer is gradually narrowed, the active layer 3 is formed.
In the method, the width of the current injection gradually decreases, and the injection current decreases. As a result, the injection density gradually decreases. Further, since the protrusion 21 of the groove is gradually narrowed, the equivalent refractive index of the waveguide portion of the transition region 12 gradually changes, and the non-injection region 13
Approach to the equivalent refractive index.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram showing the configuration of the fifth embodiment of the present invention.
Same as (b). The fifth embodiment is similar to the first embodiment shown in FIG.
The shapes of the current injection end portion 18 and the groove 6 are different from those of the embodiment of FIG. Note that FIG. 6B is a cross-sectional view of FIG.
It is a figure which shows C 'cross section.

That is, the fifth embodiment shown in FIG.
As shown in FIG. 1, from both sides of the ridge portion 14, the width gradually increases and the depth thereof becomes shallow while the groove protrusion 21-1 extending in the right direction in the drawing becomes the protrusion 22 of the ridge portion. It is formed in a substantially rectangular shape.

The etching portion 19 of the contact layer 5 is
As in the example of FIG. 6, the right side is divided by a dotted line in FIG.
On the right side of the current injection flow area 11 is a projection 18 of the contact layer.
Is etched away.

In the fifth embodiment, the current is injected through the contact layer 5 on the ridge portion 14 and the contact layer projection 18 on the ridge projection 22.
Since the protrusion 18 of the contact layer gradually becomes shallower,
In the active layer 3, as the magnitude of current injection gradually decreases, the injection density gradually decreases, and the equivalent refractive index gradually changes. In addition, since the protrusion 21-1 of the groove is gradually reduced, the equivalent refractive index of the transition region 12 gradually changes and approaches the equivalent refractive index of the non-injection region 13.

A sixth embodiment will be described with reference to FIG.
FIG. 7 is a diagram showing the configuration of the sixth embodiment of the present invention, which is an example of an embedded SLD. The buried type is also formed using the original wafer shown in FIG. 2 as in the ridge type.

In FIG. 7, (a) shows the SL of this embodiment.
D is viewed from above the original wafer, and FIG.
FIG. 3C is a diagram illustrating a cross section taken along line A ′, and FIG.

In FIG. 7, reference numeral 23 denotes a first current confinement layer;
24 is a second current confinement layer, 25 is a reflection angle conversion groove, 26
Denotes a projection of the first electrode, and other reference numerals are the same as those in FIG.

As shown in FIG. 7C, the active layer 3 is formed thin together with the second cladding layer 4 between the first current confinement layer 23 and the second current confinement layer 24. A waveguide portion is formed, and as shown from the upper side, is indicated by a dashed line in FIG. 7A.

In FIG. 7A, the contact layer 5 is formed in the entire area of the current injection area 11 and in the center of the transition area 12 surrounded by the dotted line. Is formed, and the protrusion 26 of the first electrode forming the transition region 12 adjacent to the first electrode 15 is formed so that the width gradually decreases toward the other end 20. .

The reflection angle conversion groove 25 is provided to prevent the light traveling from the active layer 3 toward the other end 20 from being reflected and returning to the active layer 3.

Next, a seventh embodiment of the present invention will be described with reference to FIG. The embodiment of FIG. 8 differs from the sixth embodiment shown in FIG. 7 in the shape of the active layer 3.

That is, in the seventh embodiment, while the width of the active layer 3 shown by the one-dot chain line gradually increases,
5 are formed.

Therefore, the reflection from the other end 20 is reduced, and the output light with little ripple in the output light spectrum can be obtained.

An eighth embodiment of the present invention will be described with reference to FIG. The embodiment of FIG. 9 differs from the sixth embodiment shown in FIG. 7 in the shape of the active layer 3 and in which the reflection angle conversion groove 25 is omitted.

That is, in the eighth embodiment, FIG.
The active layer 3 is gradually bent upward in the drawing from the transition region 12 to the non-injection region 13 as shown in FIG.
Is formed so as to reach the upper end without reaching.

Therefore, the light emitted from the current injection region 11 of the active layer 3 reaches the upper end while bending upward according to the shape of the active layer 3 between the transition region 12 and the non-injection region 13. A part leaks in the direction of the other end 20 and disappears.

In the first to eighth embodiments, light traveling from the current injection region 11 to the transition region 12 does not return to the current injection region 11, so that the ripple of the output light spectrum can be reduced by one. Emitted light reduced to about / 2 can be obtained.

Incidentally, the equivalent refractive index of the waveguide portion in the transition region 12 is almost equal to the equivalent refractive index of the current injection region 11 at the boundary of the current injection region 11.
At the boundary of the non-injection region 13, it is almost equal to the equivalent refractive index of the non-injection region 13, during which the equivalent refractive index gradually increases.

Next, the configuration of the ridge waveguide type SLD according to the first embodiment of the present invention, including the manufacturing method, will be described in detail with reference to FIGS.

(1) The original wafer shown in FIG.
The following layer structures are grown on the P semiconductor substrate 1 by MOVPE.

The first cladding layer 2 is an n-InP layer having a thickness of 1.5 μm.

The active layer 3 is an MQW layer (InGaAs)
P layer 1.31 μm composition / InGaAsP layer 1.08 μm
Composition 20 pairs) with a thickness of 0.15 μm or bulk (In
(GaAsP layer 1.31 μm composition) Thickness 0.15 μm.

The second cladding layer 4 is a p-InP layer having a thickness of 2.3 μm.

The contact layer 5 is made of p-InGaAs
The thickness of the layer is 0.6 μm.

(2) A ridge is formed.

In order to form the groove 6, the resist is patterned except for the portion where the groove 6 is to be formed. The length of the current injection region 11 is 400 to 700 μm, and the length of each of the transition region 12 and the non-injection region 13 is about 200 μm.

Using this resist as a mask, the contact layer 5 is chemically etched (H ₂ SO ₄ : H ₂ O ₂ : H ₂ O).
= 1: 1: 40) and the resist is removed.

Using the contact layer 5 as a mask, the second
Chemical etching (HCL: H ₂ O =
The active layer 3 is etched to 0.3 μm by 1.5: 1).

(3) Etching of the contact layer 5.

Using the resist as a mask, the right side contact layer 5 defined by the dotted line in FIG. 1 is etched by dry etching.

(4) Formation of oxide film and opening of window.

On the above growth surface, SiO was deposited by CVD.
₂ After forming (dielectric layer 7) to a thickness of 0.4 μm, FIG.
On the ridge portion 14 and the contact layer projection 18
Open a window of iO ₂ by dry etching.

(5) Deposition of the first electrode 15.

Ti / Pt was deposited on the growth surface by electron beam evaporation.
/ Au is deposited to a thickness of 0.02 / 0.05 / 0.2 μm, respectively.

(6) Polishing.

The lower side of the semiconductor substrate 1 is polished to a layer thickness of 120 μm by mechanical polishing. After that, chemical etching (H
Polishing to a thickness of 100 μm is performed with Cl: H ₃ PO ₄ = 1: 1).

(7) Deposition of the second electrode 16.

After polishing, Ti / Pt / Au was deposited on the lower side of the semiconductor substrate 1 by electron beam evaporation at a rate of 0.02 / 0.
Evaporate to a thickness of 05 / 0.2 μm.

(8) Alloy.

At 410 ° C. for 60 seconds, the deposited metal is alloyed.

(9) Change.

The surface on which the AR coating 17 is to be applied is cut into a bar shape.

(10) SiO of a reflectance of 0.2% is vapor-deposited on the cleavage surface and AR-coated.

(11) Cut off the chipping bar into each element.

Through the above steps, the ridge waveguide type SLD according to the first embodiment of the present invention can be manufactured.

It should be noted that the second to fifth embodiments can be manufactured in the same process except that the shape of the groove and the contact layer in the transition region 12 is different.

Next, a buried waveguide type SLD according to a sixth embodiment of the present invention will be described in detail with reference to FIGS.

(1) The original wafer shown in FIG. 2 is used.
However, the thickness of the contact layer 5 is 0.3 μm.

(2) Mesa etching Chemical etching (H ₃ SO ₄ : H ₂ O ₂ : H ₂ O =
3: 1: 1), the contact layer 5 is removed.

[0095] the upper side of the portion surrounded by the alternate long and short dash line waveguide is formed in FIG. 7 (a), 0.08μ a SiN _X film
m to form a film.

Using this SiN _x film as a mask, chemical etching (based on bromomethanol and hydrochloric acid) is carried out as shown in FIG.
The portions corresponding to the first and second current confinement layers 23 and 24 are etched to form a mesa having a width of 2 μm of the active layer 3. This mesa portion constitutes a waveguide.

(3) BH growth (Buried Het)
The buried layers of the first and second current confinement layers 23 and 24 are regrown in the portions removed by the etching.

(4) Growth of Contact Layer 5 After removing the SiN _x film, p-InGaAs is formed on the growth surface.
A contact layer 5 (p doping amount 1 × 10 ¹⁹ cm ⁻³ ) is grown to a thickness of 0.3 μm.

(5) Deposition of the first electrode 15 A part of the contact layer 5 is removed by dry etching using the resist as a mask. The part to be removed is shown in FIG.
(A) is the outside and the non-implanted region 13 of the transition region 12 surrounded by the dotted line.

On the contact layer 5, Ti / Pt / Au each having a thickness of 0.0 as the first electrode 15 is formed on the left portion of the contact layer 5 by the lift-off method.
Evaporate to 2 / 0.05 / 0.2 μm.

(6) Formation of the reflection angle conversion groove 25. (Not required in the eighth embodiment of FIG. 9) A groove 25 having a depth of 10 μm is formed by chemical etching (bromethanol) using the SiN _x film as a mask. The inclination angle on the upper surface of the groove 25 is 60 °. After forming the groove 25, S
iN _X film is removed.

(7) Polishing The lower side of the semiconductor substrate 1 is mechanically polished to a thickness of 120 μm.
Polish until After that, chemical etching (HCl: H ₃ P)
O ₄ = 1: 1) and polished to a thickness of 100 μm.

(8) Deposition of Second Electrode 16 After polishing, T was deposited under the semiconductor substrate 1 by electron beam deposition.
i / Pt / Au is 0.02 / 0.05 / 0.2 respectively
Deposit to a thickness of μm.

(9) Alloy The deposited metal is alloyed at 410 ° C. for 60 seconds.

(10) Cleavage The surface on which the AR coating 17 is to be applied is cleaved in a bar shape.

(11) SiO having a reflectivity of 0.2% is vapor-deposited on the cleavage surface and AR-coated.

(12) Separate the chipping bar into each element.

Through the above steps, an embedded waveguide SLD according to the sixth embodiment of the present invention can be manufactured.

It should be noted that the seventh to ninth embodiments can be manufactured in the same process except that the shapes of the buried layer in the transition region 12 and the non-injection region 13 are different.

An example of the use of the SLD according to the embodiment of the present invention will be described.

First, when used as a carrier for wavelength division multiplexing communication, the wavelength spectrum of the SLD of the present invention is:
Since 1.53 μm to 1.56 μm is covered, and the intensity ripple between them is as small as 2.5%, it is possible to extract light of a required wavelength from the light with a filter and use it as a carrier with less ripple due to wavelength. it can.

When using as the reference wavelength light of the optical spectrum analyzer, the output of the SLD of the present invention is
1.555μ by passing ₂ H ₂ (acetylene) gas
By creating a light absorption spectrum of m and displaying it on the drawing of the optical spectrum analyzer, it is possible to calibrate the 1.555 μm point on the wavelength axis (horizontal axis).

[0113]

The superluminescent diode according to the present invention comprises a semiconductor substrate 1, a first cladding layer 2 formed on the semiconductor substrate, and a light-emitting end formed on the first cladding layer. An active layer 3 serving as an emission end of the second layer, a second cladding layer 4 formed on the active layer,
A contact layer 5 formed on the cladding layer, a current injection portion 14 extending in a stripe shape from the emission end side to the other end side on the contact layer, and injecting a current into the active layer; In a super luminescent diode provided with a current injection region 11 defined by a tip of a current injection part, a current injection end part in which a width of a stripe gradually decreases from the tip of the current injection part toward the other end. 18
Thus, between the current injection region and the non-injection region 13 where no current is injected, a transition region 12 where the current to be injected gradually decreases from the current injection region toward the non-injection region is formed. Therefore, a sharp change in the equivalent refractive index can be prevented at the end of the current injection portion 14 of the current injection region 11 to provide a super luminescent diode having no intensity modulation in the emission spectrum.

A super luminescent diode according to a second aspect of the present invention includes a semiconductor substrate 1, a first cladding layer 2 formed on the semiconductor substrate, and a super cladding layer formed on the first cladding layer. An active layer 3 having one end as a light emitting end, a second cladding layer 4 formed on the active layer, a contact layer 5 formed on the second cladding layer, A current injection portion 14 extending in a stripe shape from the emission end side to the other end side for injecting a current into the active layer; a current injection region 11 defined by a tip of the current injection portion; In a super luminescent diode provided with ridge-forming grooves 6, 6 provided along both sides to form an injection portion in a stripe shape, the current injection portion extends from the tip to the other end. T Current injection end 22 extending stripe shape
And a groove end portion 21 provided along both sides of the current injection end portion and having a width gradually reduced from the tip of the current injection portion toward the other end side, so that the current injection region and the current Between the current injection region and the non-injection region, the transition region 12 in which the equivalent refractive index gradually increases from the current injection region to the non-injection region.
The super luminescent diode according to claim 3 of the present invention includes a current injection end portion 22 extending in a stripe shape from the tip of the current injection portion to the other end side, and along both sides of the current injection end portion. The super luminescent diode according to claim 4 of the present invention is provided with a groove end portion 21-1 having a depth gradually decreasing from the tip of the current injection portion toward the other end side. A current injection end portion 18 in which a stripe width is gradually narrowed from the tip of the current injection portion toward the other end side; and a current injection end portion 18 provided along both sides of the current injection end portion and the other end side from the tip of the current injection portion. The super luminescent diode according to claim 5 of the present invention has a stripe width from the front end of the current injection section toward the other end side. Gradually narrowing the current injection end 18
And a groove end 21-1 provided along both sides of the current injection end and gradually decreasing in depth from the tip of the current injection portion toward the other end. By forming the transition region 12 in which the equivalent refractive index gradually increases from the region to the non-injection region, the current injection region 1
1 can be reduced, and the intensity modulation of the emission spectrum can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an original wafer used in an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a fifth exemplary embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a sixth embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a seventh exemplary embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of an eighth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional superluminescent diode.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor substrate 2 first cladding layer 3 active layer 4 second cladding layer 5 contact layer 6 groove 7 dielectric layer 8 etch stop layer 11 current injection region 12 transition region 13 non-injection region 14 ridge portion 15 first electrode (Current injection part) 16 Second electrode 17 AR coating 18 Contact layer protrusion (current injection end) 19 Contact layer etching part 20 Other end 21 Groove end (groove protrusion) 22 Ridge part protrusion 23 First Current Narrowing Layer 24 Second Current Narrowing Layer 25 Reflection Angle Conversion Groove 26 Projection of First Electrode

Claims (5)

[Claims] 1. A semiconductor substrate (1), and a first cladding layer (2) formed on the semiconductor substrate.
An active layer (3) formed on the first cladding layer and having one end as a light emitting end; a second cladding layer (4) formed on the active layer; and the second cladding A contact layer (5) formed on the layer; a current injection portion (14) extending in a stripe shape from the emission end side to the other end side on the contact layer for injecting current into the active layer; A current injection region (1) defined by a tip of the current injection unit;
1) a super-luminescent diode comprising: a current injection end portion (18) in which the width of a stripe gradually decreases from the tip of the current injection portion toward the other end side; A transition region (12) in which a current to be injected gradually decreases from the current injection region to the non-injection region is formed between the injection region and a non-injection region (13) to which no current is injected. And a super luminescent diode. 2. A semiconductor substrate (1), and a first cladding layer (2) formed on the semiconductor substrate.
An active layer (3) formed on the first cladding layer and having one end as a light emitting end; a second cladding layer (4) formed on the active layer; and the second cladding A contact layer (5) formed on the layer; a current injection portion (14) extending in a stripe shape from the emission end side to the other end side on the contact layer for injecting current into the active layer; A current injection region (1) defined by a tip of the current injection unit;
1) a ridge-forming groove (6, 6) provided along both sides to form the current injection portion in a stripe shape;
A superluminescent diode comprising: a current injection end portion (22) extending in a stripe shape from the tip of the current injection portion toward the other end; and provided along both sides of the current injection end. A groove end (21) whose width gradually decreases from the tip of the current injection part toward the other end side is provided, so that between the current injection area and the non-injection area (13) where no current is injected. A transition region (1) where the equivalent refractive index gradually increases from the current injection region to the non-injection region.
2. A super luminescent diode characterized by forming 2). 3. A semiconductor substrate (1), and a first cladding layer (2) formed on the semiconductor substrate.
An active layer (3) formed on the first cladding layer and having one end as a light emitting end; a second cladding layer (4) formed on the active layer; and the second cladding A contact layer (5) formed on the layer; a current injection portion (14) extending in a stripe shape from the emission end side to the other end side on the contact layer for injecting current into the active layer; A current injection region (1) defined by a tip of the current injection unit;
1) and a ridge forming groove (6, 6) provided along both sides to form the current injection portion in a stripe shape.
6), a current injection end portion (22) extending in a stripe shape from the tip of the current injection portion toward the other end, and along both sides of the current injection end. A groove end (21-1) is provided, the depth of which is gradually reduced from the tip of the current injection portion toward the other end side, so that the current injection region and the non-injection region where no current is injected ( 13), the transition region (1) where the equivalent refractive index gradually increases from the current injection region to the non-inflow region.
2. A super luminescent diode characterized by forming 2). 4. A semiconductor substrate (1), and a first cladding layer (2) formed on the semiconductor substrate.
An active layer (3) formed on the first cladding layer and having one end as a light emitting end; a second cladding layer (4) formed on the active layer; and the second cladding A contact layer (5) formed on the layer; a current injection portion (14) extending in a stripe shape from the emission end side to the other end side on the contact layer for injecting current into the active layer; A current injection region (1) defined by a tip of the current injection unit;
1) a ridge-forming groove (6, 6) provided along both sides to form the current injection portion in a stripe shape;
A current injection end (18) in which a stripe width gradually narrows from the tip of the current injection portion toward the other end, and along both sides of the current injection end. A groove end portion (21) whose width is gradually reduced from the tip of the current injection portion toward the other end side, so that the current injection region and the non-injection region (13) to which no current is injected are provided. A transition region (12) in which the current to be injected gradually decreases and the equivalent refractive index gradually increases from the current injection region to the non-injection region. St diode. 5. A semiconductor substrate (1), and a first cladding layer (2) formed on the semiconductor substrate.
An active layer (3) formed on the first cladding layer and having one end as a light emitting end; a second cladding layer (4) formed on the active layer; and the second cladding A contact layer (5) formed on the layer; a current injection portion (14) extending in a stripe shape from the emission end side to the other end side on the contact layer for injecting current into the active layer; A current injection region (1) defined by a tip of the current injection unit;
1) a ridge-forming groove (6, 6) provided along both sides to form the current injection portion in a stripe shape;
A current injection end (18) in which a stripe width gradually narrows from the tip of the current injection portion toward the other end, and along both sides of the current injection end. A groove end portion (21-1) having a depth gradually decreasing from a tip of the current injection portion toward the other end side, so that the current injection region and a non-injection region to which no current is injected are provided. A transition region (12) is formed between the current injection region and the non-injection region, in which a current to be injected gradually decreases and an equivalent refractive index gradually increases. Super luminescent diode.